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Geography and the Environment: Graduate Student Capstones Department of Geography and the Environment
5-22-2013
Spacing Units in the Greater Wattenberg Area
Tera Dillon
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Recommended Citation Dillon, Tera, "Spacing Units in the Greater Wattenberg Area" (2013). Geography and the Environment: Graduate Student Capstones. 34. https://digitalcommons.du.edu/geog_ms_capstone/34
This Capstone is brought to you for free and open access by the Department of Geography and the Environment at Digital Commons @ DU. It has been accepted for inclusion in Geography and the Environment: Graduate Student Capstones by an authorized administrator of Digital Commons @ DU. For more information, please contact [email protected],[email protected]. Spacing Units in the Greater W attenberg Area
T e ra D illo n University of Denver D epartm ent of Geography Capstone Project fo r M a ste r o f S c ie n c e in G e o g ra p h ic In fo rm a tio n S c ie n c e
22 M ay 2013
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A b stract Horizontal w ells are the m ost com m only drilled w ells in the W attenberg
Field, located in W eld County, Colorado. Petroleum engineers have becom e interested in determining how m any horizontal w ells can econom ically be drilled per section in th is vertically, w e ll- developed field. U sing the Colorado
O il and G as Conservation Com m ission’s spacing unit regulations as a guide, a G IS workflow was developed to create the deliverables required for further analysis. S pacing units w ere created by applying a buffer to horizontal w ell surveys, and using th is bu ffe r to se lect inte rse cting qu arte r- qu arter section s.
The selected quarter- quarter sections w ere sim plified using the dissolve tool and then spatially joined to producing w ells. The resulting tabular data is exported, edited, and form atted for delivery to engineers for subsequent a n a ly s is .
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T ab le of Contents A bstract...... ii Tables and Figures ...... iv List of A bbreviations ...... v In trodu ction ...... 6 Background ...... 7 A P I N u m b e rs ...... 7 Drilling Te chniques ...... 9 Directional Surveys ...... 9 P ro je ct A rea ...... 10 Intent ...... 11 Literature Review ...... 13 Spacing U nits ...... 13 G IS in O il & G as Produ ction ...... 14 G IS for D ata In te gration ...... 16 Design and Im plem entation...... 17 Data and Sources ...... 17 Data Dictionary...... 19 M ethodology ...... 21 Data M anagem ent...... 21 Building S pa c in g U n it s ...... 28 Tying Spacing U nits to Producing W ells ...... 37 Preparing the Table for delivery ...... 38 R e s u lt s ...... 40 D is c u s s io n ...... 40 A reas for Further R esearch ...... 41 Glossary of Term s ...... 43
W orks Cited ...... 44
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Tables and Figures Figu re # 1 , W atte n be rg Location ...... 11 Table #1, Layers & Sources...... 18 T a b le #2, G W A Spacing Unit G eodatabase Details ...... 20 Figure #2, Culture Feature Dataset ...... 22 Figure #3, W ell Feature Dataset ...... 28 Figure # 4, Spacing U nit O verlap ...... 30 Figure # 5, Spacing U nit Creation G uides ...... 32 Figure # 6, W ells w ithout Directional Surveys ...... 33 Figure #7, Buffering and Quarter- Q uarter S election Errors ...... 35 Figure # 8, Suspicious W ell Bores ...... 36 Figure # 9, Sp acing Unit Feature Dataset ...... 37 Table #3, Layers & Sources...... 39
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L is t o f A b b r e v ia tio n s
API- A m e ric a n P e tro le u m In s titu te
BH- Bottom Hole
COGCC- Colorado Oil and Gas Conservation Com m ission
DJ- Denver- Julesburg
G IS - Geographic Inform ation Sys te m
GW A- Greater W attenberg Area
Loc- Location
S u rf- S u rfa c e
TD- T o ta l D e p th
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In trod u ction Noble Energy, Incorporated (Noble) is a leading independent energy com pany engaged in worldwide oil and gas exploration and production. The
Com pany has dom estic, on sh ore, core operations in the Denver- Julesburg
(D J) basin , the Marcellus Shale, as well as in the deepwater G ulf of M exico areas in the United States (Noble Energy Inc. 2013 , 1 ). T h is p r o je ct focu ses on the G reater W atte n be rg A rea, a subset of the W atte n be rg F ield, in th e D J
Basin, in Northern Colorado.
The state of Colorado, like the U nited S tates of A m erica, has a rich history of o il and gas exploration and production. The state was hom e to the second d o m e s t ic d is c o v e r y o f o il in 1861 ( R a n d a ll 2 0 09, 1 ). The W a t t e n b e r g F ie ld is one of the largest fields in the United States and the m ost active drilling area in C olorado. It w a s discovered in 1970 (Sonnenberg 2006, 5 ), a n d currently h o ld s over t w e n ty thousand wells (C olorado P u b lic R a d io 2012). I n 2009, th e
Energy Information Adm inistration ranked W atte n be rg as th e te n th large st gas, an d th e th irte e n th large st oil field in th e U n ited S tate s (2004, 1).
Considering the technologic and regulatory advances in the last four years, th is statistic is su rely dated.
Despite the stereotype, oil and gas developm ent is approached with anything but a “ w ild w e s t ” m e n t a lit y . In the industry’s infancy we lls w ere d r ille d haphazardly, nearly on top of each other, in an atte m pt to follow an
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underground “river of o il.” Fortu n ate ly, m odern sc ie n ce has brought new understanding to the industry, along with com prehensive rules and regulations . P rotecting preciou s, n on - renewable, petroleum resou rces, th e people who extract them , and the general public are now an essential part of the oil and gas industry and its regulatory counterparts.
Spacing units are one of the sign ifican t r e g u la t io n s governing the drilling and production of oil and gas. They are defined by Schlum berger as an area allotted to a w ell by regulations, or field rules, issued by a governm ental authority having jurisdiction for the drilling and production of a w ell (2013).
S pacing units are designed to prevent th e d r illin g o f u n n ecessary w ells, a v o id th e w aste o f h ydrocarbon resou rces, an d to prote ct th e in terests of all invested parties (Montana Code 2011). N e a r ly e very state w ith drilling activity has som e form of w ell spacing regulation. The st ate of Colorado is no exception. I n th e state th e re gu latory body w it h ju r is d ic t io n o v e r oil and gas w e lls is the Colorado O il and G as Conservation C o m m is s io n (COGCC). The com m ission ’s R ule 318A s p e lls out the spacing unit requirem ents for the
G reater W attenberg Area (GW A) and will serve as a guide for this analysis.
Background
API Num bers To be st u n de rstan d th e m e th odology laid ou t in late r se ction s, it is im portan t to have a basic understanding of a few standard industry term s and practices. Hundreds of thousands, if n ot m illion s, of w ells have been drilled
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in th e U n ited S tate s. Each well is identified by a unique, permanent, num eric id e n t ifie r , c a lle d an A m e rican Pe troleu m In stitute (API) num ber (A m e r ic a n
Pe troleu m In stitute 1979, 1 ). Today’s standard API num bers are 14 digits in l ength and are broken into five portions as follows:
05- 123- 12345- 01- 02
The first two digits on an API num ber designate the State in which a well is drilled; the “05” above denotes a w ell drilled in Colorado. The next three digit num ber refers to the county in w h ic h t h e w e ll w a s d r ille d ; t h is c o d e , a s a general rule, m atches the Federal Information Processing Standard, or
FIP S co d e . In this exam ple “123” in d ic a t e s t h e w e ll w a s d r ille d in W e ld
County. The five digit portion of an API num ber is the “ Unique W ell C o d e ,” these num bers are assigned by the regulatory body, u s u a lly con secu tively.
The final tw o sets of two digit num bers designate a w ell’s side track and recom pletion statu ses respectively. A sidetrack occu rs w h en a secon dary w e llb o r e is d r ille d a w a y from the original. S idetracks are drilled for a variety of reasons including testing new formations, avoiding unstable geology, or du e to other drilling related issues. Each sidetrack is sequentially num bered.
A recom pletion is essentially a repair perform ed to a wellbore, restorin g a w e ll’s p r o d u c t iv it y . M any vertical wells in the G W A have been recom pleted three or m ore times, creating three or m ore API num bers. W hen no sidetracks or recom pletions have been perform ed, these num bers are zeros.
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D rillin g T echniques Today there are three m ethods to drilling an oil or gas w ell. V ertical drillin g is a s o ld a s t h e o il a n d g a s in d u s t r y it s e lf. This m ethod entails placing a w ell directly above a target and drilling straight down to tap into oil or gas reserves. The secon d m eth od is dir e c t io n a l d r illin g . This m ethod entails th e intentional deviation of a w ellbore from it s n a t u r a lly occurring path by exploiting v a r io u s drilling param eters such as w eight on bit or rotary speed
(Schlum berger 2013) . U t iliz in g t h is drilling technique, oil or gas reserves can be tapped w ith strategically placed w ells. The final drilling technique , a n d focu s of th is project, is h o r iz o n t a l d r illin g , w h ic h is an extension of directional d r illin g . H orizon tal w ells begin drillin g like a ny oth e r v e r t ic a l w e ll u n t il th e y d r ill d o w n t o th e designated “ k ic k - out” point. This point is the m easured depth where the b it b e g in s t o d e v ia t e fr o m v e r t ic a l, pushing out u n t il reaching a ninety degree angle. A t th is poin t th e w ell is drilled h orizon tally until reaching its total depth (TD ).
D irectional Surveys In the state of Colorado every horizontal or directional well d r ille d is required to have a directional survey perform ed an d su bm itted to th e C O G C C .
Directional surveys are attained by feeding a tool into a wellbore to m easure its depth, inclination from vertical, and azim uth (or com pass heading). These m easurem ents are then used to delineate a wells’ three dimensional path within the earth on a tw o dim ensional m ap. These surveys play an important
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role in shaping a w e ll’ s spacing u n it. W here a well has been drilled w it h in a section determ ines which quarter- qu arte r se ction s m ak e u p its spacing unit.
Project Area The G W A is defined by the CO G CC as the area between Townships 2 South to 7 North, and Ranges 61 W est to 69 W est, 6th P r in c ip le M e r id ia n . F ig u r e o ne shows a m ap of the G W A area and the oil and gas w ells drilled in the area.
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Figure #1, W attenberg Location Intent Due to the GW A’s long and dynam ic history, m any of the current ac t iv e , o r producing, w ell bores are vertical or directional in nature. W it h the advent and increasing popularity of h orizon tal drillin g Noble and other com pan ies are faced with a n u m b e r o f im portan t d e c is io n s. F ir s t , are v e r t ic a l w e lls draining reservoir rocks adequately? W o u ld horizontal w ells be m ore
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effective? Are they econom ically feasible ? How m any horizontal w ells can be d r ille d per section in a h istorically, vertic a lly d r ille d fie ld ?
Narayan Choudhary, an engineer with Noble w as task e d w ith answering these questions. His approach hinged on determ in in g the num ber of vertical, directional, and w hen applicable horizontal w e lls , are producing w it h in a h orizontal spacing unit. In order to accom plish th is, spacing units need to be created for each horizontally d r ille d w e ll in the GW A. T hen the producing wells need to be tied to the spacing units.
U nfortunately, the standard, geologic, G IS program used at Noble, IH S ’
P e tra , is not capable of efficien tly perform ing the required analytical steps.
T h is software is focused on wellbores, and therefore views the world vertically. To e n te r an y th ing into th e database , th e data m u st be tied to a specific location in a w ellbore. In other words, instead of an X/Y location,
Petra only requires a Z , or depth value. Th at’s n ot to say Pe tra doe sn ’t require an X /Y location, it relies on the w ell location for that inform ation.
A nother com plication to using Petra is its inability to perform the basic geoprocessing tools available in ArcG IS softw are. U t iliz in g ArcGIS and th e geoprocessing tools, a finished M icrosoft E xcel w orkbook can be produced in a relatively short am ount of tim e. Narayan can then use this data, to acquire production values and perform the required, engineering analysis.
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Literature R eview
S p a c in g U n its A side from regulations and law review s, there is very little w ritten about spacing units; a regulation, governing the drilling and production of oil and gas. P r e v io u s ly d efined as an area allotted to a w ell by regulations, or field ru les, issued by a governm ental authority having jurisdiction for the drilling and production of a well; spacing units prevent the drilling of unnecessary w e lls , a v o id w a s t in g hydrocarbons, and protect invested parties (M ontana
Code 2011). M ineral owner s , an inv e ste d party , have “correlative rights,” or th e righ t to de v e lo p t h e ir m in e r a ls ( H o ffm a n 2011, 3 8 ). These rights cannot infringe upon other nearby m ineral owners. There are m any scenarios in which an infringem ent can occur. A trespass transpires w hen a w ell is drilled too near a lease line and drains resources from the neighboring lease
(Hoffman 2011, 3 8 ). In the state of C olorado, w ells are to be drilled no less than six hundred feet from any lease line to prevent trespass (CO G CC 2013,
32). However, each m ineral ow ner can “captu re” oil and/or gas under their property before it flows off of their property and onto the next.
Another infringem ent occurs when wells are drilled too closely together. T h is im proper spacing results in a drop in reservoir pressure and com prom ises production (Haines 2006, 9 5 ) . In th is case, spacing u n its protect th e reservoir’s ability to produce, as w ell as protecting the m ineral ow ner’s rights to exploit “their” hydrocarbons.
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G IS in O il & G a s P r o d u c tio n Given the nature of the data, geographic inform ation system s have been used in the conventional oil and gas industry for som e time. The ability to spatially view tabular w ell data is vital to the industry. To achieve this, a num ber of industry specific G IS are available including Petra , G eographix,
Pe tre l, e tc.; e ach w ith th e ability to acce pt for im port an d cre ate for e x port
ESRI shapefiles. “W ith recent advances in the software, broadening its capabilities, m aking it easier to use, and an increased awareness, the num ber of ArcGIS users has grown dram atically (Petroleum G IS Perspectives
2009/2010, 6 ). From m apping and analysis to data m anagem ent ArcG IS is gaining ground in the oil and gas industry.
O ne exam ple of GIS being used in the industry is the m erger of Statoil and
H ydro O il and G as. In October of 2007 the Norwegian Statoil Energy
Com pany m erged w ith N orsk Hydro’s O il and G as Division, creating
StatoilHydro. The new ly created, com pany utilized G IS in nearly all phases of its business including business developm ent, exploration, field developm ent, production, and dow nstream retail (Petroleum G IS Perspectives 2009/2010,
6 ). A t S tatoil, and every oil and gas com pany, G IS is integrated into every division dealing w ith spatial data. For exam ple, facilities developm ent, u t iliz e s s p a t ia l data for installation and operational support, w hile pipeline installation and inspection, m arine surveillance, and environm ental studies also m ake u se of G IS .
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M ore ov e r, in 2 0 0 3 , afte r obtaining a gran t from th e U n ited S tate s
Department of Energy (DOE), th e A lask a D e partm e n t of A dm inistration , an d the Alaska O il and G as Conservation Com m ission (AO G CC) collaborated to create a com prehensive, GIS based website for Alaska’s oil and gas data.
Three goals were identified for the project; first, publish geo- te ch n ic a l inform ation, autom ation of reviews of exploration and developm ent projects, and third, create a shared G IS to be used am ong state agencies (Fed.
Energy Tech. Center 2003, 3 ), along w ith oil and gas industry professionals and the general public. G IS w as utilized in accom plishing all three goals. The fir s t g o a l, p u b lis h in g g e o - technical inform ation, used G IS to quality control the non- confidential directional surveys (w ell sticks) as w ell as for the delineation of oil producing basins agencies (Fed. Energy Tech. Center 2003,
3 ). The second goal was accom plished in conjunction with the third. A s th e shared, m ulti- agency, G IS took shape, functionality perm itting applicants to locate project boundaries via either a m ap interface or a text description was i ncluded, agencies (Fed. Energy Tech. Center 2003, 8 ). T h is fu n c t io n a lit y aided in the fulfillm ent of autom ation in respect to review s of exploration and developm ent projects.
Finally, com pletion of the third goal created an enterprise level G IS populated by state agen cies, an d u tilized by th ose agen cies, indu stry professionals, and the general public agencies (Fed. Energy Tech. Center
2003, 9 ). The com pleted w ebm ap can be found at:
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http://dog.dnr.alaska.gov/PublicG IS/. T h is w e b m a p is a rem arkable exam ple of a fully integrated w eb m ap; it brings together data from m ultiple agencies an d creates valuable product.
G IS for D ata Integration M e rriam - W ebster’s defines integration as form ing, coordinating, or blending in to a functioning or unified whole (2012). G IS data inte gration is on e of th e m ost im portant topics in the w hole field of G IS (Flow erdew 1991, 375). A s it continues to becom e a core com ponent of the enterprise landscape, the need to integrate G IS w ith other traditional enterprise applications is becom ing m ore apparent. G enerally speaking, G IS integration involves m e sh ing spatial or attribu te data into a h om oge n e ou s datase t,
(Scheepm aker 2007, 7 ). The third phase of the AOGCC project exem plifies a w e ll- e x e cu te d data inte gration ou tcom e .
In an attem pt to sim plify the process of geotherm al exploration in Iran, a team of scientists built a series of G IS m odels to integrate exploration, environm ental, and w ell data (N oorollahi 2008 , 108) . T h e fir s t m o d e l w a s bu ilt to inte grate e x ploration data. Th is dataset included volcan ic rocks, faults and fractures, acidic hydrothermal alteration zones, hot springs, and low electrical resistivity. Using a Boolean m odel, each layer was weighted, com bined, and/or m erged; resulting in a “M ost favorable area for geotherm al resource exploration” raster layer (N oorollahi 2008, 119). The sam e Boolean m odel w as used to create an “Environm ental Suitability” layer
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from the environm ental layers: topology, surface drainage, residential area, land use, and vegetation cover and density (Noorollahi 2008, 124- 125).
Finally, the tw o created layers w ere com bined into a “S ite S uitability Index” m ap, identifying high priority areas for exploratory drilling (Noorollahi 2008,
130).
The planning department of Langley Township, British Colum bia is another instan ce of successful data integration . Th e departm en t su ccessfully integrated their aerial imagery, with parcel and land m anagem ent data into a w eb m apping tool. U s in g the web- m apping tool, property data located in a
Land M anagem ent System was charted on top of existing aerial imagery.
Th is su ccessful integration le veraged each applications’ “touch points” to integrate the existing web- m apping tool w ith the Land M anagem e n t S y ste m
(Scheepm aker 2007, 2 8 ). B y utilizing an existing application, not only w as the desired level of integration achieved, but end user training was m in im iz e d .
D esign and Im plem entation
Data and Sources Th e data used for th is an alysis was collected from a variety of pu blic sou rces. T a b le o n e details each data layer and it s sou rce.
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T a b le # 1 , L a y e r s & S ou rces E ntity Feature Source S tate B ou n daries Polygon US Census h ttp://w w w .cen su s.gov/ County Lines Polygon US Census h ttp://w w w .cen su s.gov/ Townships Polygon G eocom m unicator http://www.geocom m unicator.gov/ S e c t io n s Polygon G eocom m unicator http://www.geocom m unicator.gov/ Q u arte r S e ction s Polygon G eocom m unicator http://www.geocom m unicator.gov/ W e lls - B ottom P o in t COGCC Hole Locations h ttp://cogcc.state.co.us/ W e lls - S u rfa ce P o in t COGCC Locations h ttp://cogcc.state.co.us/ W e ll D e v ia t io n s L in e COGCC ( W e ll S t ic k s ) h ttp://cogcc.state.co.us/
D e s p it e t h e o r ig in a l s o u r c e , e ach shapefile listed in t a b le one w as dow nloaded w ith the sam e Datum and Projection information. Shapefiles obtained were unp ro je cted, however they were all assigned th e N orth
Am erican Datum of 1983. Before being integrated into the S p a c in g U n it geodatabase, each layer was projected to th e U niversal Trans verse
M e rcator, North Am erican Datum 1983, Zone 13 North projection in U n it e d
S tate s f eet. Th is projection w as ch osen to m atch th at of oth er G IS system s u sed w it h in N o b le . It is very likely th at th e created sh a p e file s w ill b e im porte d into Pe tra or oth e r G IS sy ste m s.
The w ell location and directional survey layers are updated by the CO G CC d a ily . The Shapefiles used for analysis were accessed on the 3 rd o f A p r il
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2013 . If furth er an alysis is desired, reacqu iring th ese shapefile s is recom m ended.
Data Dictionary Table tw o de m on strate s th e stru ctu re of th e G W A S pacing U n it ge odatabase .
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T a b le # 2, GW A Spacing Unit Geodatabase Details G W A Spacing U nit G eodatabase Culture Feature D ataset Feature Class Type So urce CO_Counties Polygon BLM G eocom m unicator C O _ S tate Polygon BLM G eocom m unicator G W A _ Q trQ tr_ Se ction s Polygon BLM G eocom m unicator GW A_Sections Polygon BLM G eocom m unicator GW A_Townships Polygon BLM G eocom m unicator W BU_GW A_Boundary Polygon C reated From G W A _Tow nships
SpacingUnits Feature D ataset Feature Class Type So urce G W A_SpacingU nit_Report P o in t C reated from GW A_SpacingUnits_QC & GW A_Prod_W ells_BH GW A_SpacingUnits Polygon Created from G W A_W B_Buff & G W A _ Q trQ tr_ Se ction s G W A_SpacingUnits_Dissolve Polygon Created from G W A_SpacingU nits GW A_SpacingUnits_QC Polygon C reated from G W A_SpacingUnits_Dissolve
W ellData Feature D ataset Feature Class Type So urce GW A_BH_Loc P o in t Clipped from CO G CC W ell Bottom Hole Locations G W A _D irSurvey L in e Clipped from CO G CC W ell D e v ia t io n s GW A_Horiz_BH_Loc P o in t From G W A_BH_Loc GW A_Horiz_W ellBores L in e From G W A _D irSurvey GW A_Prod_W ells_BH P o in t From G W A_BH_Loc & GW A_Surf_Loc GW A_Surf_Loc P o in t Clipped from CO G CC W ell Surface Locations GW A_W B_Buff Polygon Created by Buffering GW A_Horiz_W ellBores
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M ethodology
Data M anagem ent The Colorado State b ou n dary (“C O _ S tate ”) and Colorado counties
(“C O _Counties”) were imported into the “Culture” feature dataset of the file geodatabase as is. However, other datasets dow nloaded from the CO G CC and the BLM Geocom m unicator w e b s it e s are extrem ely large. B ecau se m ost of th is data is ou tside th e scope of th is project, the rem aining sh a p e file s w ere scaled back to focu s on data found in the im m ediate vicinity of the
GWA. A secondary effect of the e x te n t re du ction w ill b e im p r o v e d s o ft w a r e perform ance, and a reduction in size of the geodatabase.
T ownships, section s, an d qu arte r- qu arter section s one township outside of the GW A (within 8N- 70W and 3S- 60W ) were im porte d into th e geodatabase.
The overrun a llo w s fo r a n y horizontal w ells just in s id e the perimeter of the
G W A to be included in analysis. These layers are nam ed, “ GWA_To w n sh i p s,”
“G W A _ S ectio n s ,” an d “G W A _ Q trQ tr_ Se ction s” in th e “Culture” feature dataset of the file geodatabase. A G reater W attenberg Area square feature class was also created. This layer was vital for the initial data m anagem ent tasks. A squ are stretch ing from tow n sh ip 7 N - 61W to 2S- 6 9 W , th is fe atu re class w as incorporate d into th e “C u lture ” fe atu re datase t o f t h e file geodatabase as “W BU _G W A_Boundary.” The follow ing flow chart, figure two, depicts the workflow involved in creating the feature classes in the Culture
Fe atu re D atase t.
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Townships GW A_Townships (B LM Geocom m unicator)
S e c tio n s Select Inside: GW A_Sections (BLM Geocom m unicator) 8N - 70W & 3S- 60W
Q u a rter- Quarter Sections G W A _Q trQ tr_Sectio n s (BLM Geocom m unicator)
Colorado State (U S C en su s)
Colorado Counties (U S C en su s) Culture Feature Dataset GW A Spacing Unit Database
GW A Boundary (WBU_GW A_Boundary)
Figure #2, Culture Feature Dataset
A fte r incorporating cu lture data into th e ge odatabase , atte n tion tu rn ed to the sizeable task of m anipulating w ell data into suitable form ats. W e ll d a t a acquired from the COGCC includes all oil an d gas w ells drilled in th e state.
Using the batch clip function, su rface location , deviation surveys (w e ll sticks) , a n d two instances of bottom hole location w ere used as input data se ts; the G W A square was the clip feature. The resulting shapefile s ,
“G W A _ S u rf_ Loc,” “GW A_Horiz_W ellBore s ,” “ GW A_Prod_W ells_BH,” and
“G W A _ H o r iz _ B H _ L o c,” respectively were im porte d into th e “W e llData” feature dataset of the file geodatabase.
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T h ese fou r featu re classes included p e r m it t e d w e lls . Because perm itted wells are m erely planned, both t h e ir surface and bottom hole lo c a t io n s m a y change or they m ay not be drilled a t a ll for a variety of reasons. A s su ch , these perm itted locations were rem oved to ensure the integrity of the a n a ly s is . For the “G W A_Horiz_W ellBores,” “G W A_Prod_W ells_BH,” and
“G W A _ H oriz_ B H _ Loc,” th e “B H _ S tatu s” attribu te c la s s ifie d w e lls a s either
“active” or “plan n ed;” th e “plan n ed” records were selected and deleted fro m t h e featu re classes . Th e process for su rface lo c a t ions, (“G W A_Surf_Loc”), was sligh tly differen t as th e classification system is n ot th e sam e . W e lls in th is featu re class were divided into th irte e n diffe re n t classification s. W e lls classified as perm its (X X ), oil an d gas w ells con verted to dom estic w ater wells (DM ), and abandoned locations (AL) in th e “facility_s” attribu te w e re rem oved.
The “GW A_Horiz_W ellBore s ,” and “GW A_H o r iz _ B H _ Loc,” featu re classes c o n t a in ed data for both directionally and horizontally drilled w ells. B ecau se th is project focuses on horizontal spacing units, the directional w ells a n d w e ll bores needed to be rem oved from their r e s p e c t iv e featu re classes.
Unfortunately, t h e “ G W A _ H o r iz _ W e llB o r e s ,” featu re class did n o t contain an attribute to classify w ell bores as horizontal o r d ir e c t io n a l. There is, however, a “deviation_” attribu te in th e “GW A_H oriz_ B H _ Loc,” featu re class.
Fortu n ate ly, both la y e r s have a ten digit API num ber attribu te; “E T_ ID ” in the W ellBore layer, and “API” in the BH_Loc layer. A one to one tabular join
Spacing Units in the Greater W attenberg Area D illo n - 24
w as cre ate d u sing th e se tw o attribu te s. The “G W A _ B H _ Loc,” featu re class w as identified as the join table, w hile “G W A_Horiz_W ellBores,” w as utilized as th e targe t table. A fte r th e join, w e lls c la s s ifie d a s “directional” in the
“de v iation _ ” attribu te of both “G W A_Horiz_W ellBores,” and
“G W A _ H oriz_ B H _ Loc,” featu re classes were selected and deleted. T he join was rem oved. The next e d it in g t a s k perform ed on the two horizontal feature classes is to rem ove previou s w ell b ore entries. There were a num ber of w e lls t h at had been sidetracked at least once. W h e n a w e ll is s id e t r a c k e d , the original w ell w ill not produce, and is therefore not needed for later a n a ly s is . T h e o r ig in a l w e ll b o r e s , and in a few instan ces, th e first sidetracks were rem oved from the “G W A _H oriz_W ellBores” featu re class. T h e fin a l horizontal w ell count for analysis is 455 wells.
T h e fin a l w e ll data m anagem ent task is to create a bottom hole lo c a t io n layer for a ll w e lls producing in the G reater W attenberg Area. T h is la y e r needs to include bottom hole locations for horizontal, directional, and v e r t ic a l w e lls . The bottom hole location is used because that is where a vertical or directional w ell produces from . W hile horizontal w ells produce d iffe r e n t ly , th e b o t t o m h o le lo c a t io n o f t h o s e w e lls is c lo s e r t o th e point of production than the surface location. The “GW A_Prod_W ells_BH” feature class w as created in the geodatabase by clipping the CO G CC’s bottom hole lo c a t io n s h a p e file , and then rem oving the p la n n e d w e lls . A s su ch , th e
“GW A_Prod_W ells _BH” feature class only includes directionally and
Spacing Units in the Greater W attenberg Area D illo n - 25
horizontally d r ille d w e lls . However, the m ajority of the wells in the G W A predate these drilling techniques. V ertical w ell locations w ill be added from the G W A_Surf_Loc file. Th e su rface location is u sed for vertical w e lls , because for all intents and purposes, the surface and bottom hole locations are the sam e. A one to one tabular join needed to be created between
“GW A_Prod_W ells _BH” an d “GW A_S u rf_ L o c.” Unfortunately, th e se tw o featu re classes do n ot sh are a com m on attribu te . “GW A_Prod_W ells_BH” had a te n digit API num ber in the “A PI” field w h ile “G W A _ S u rf_ Loc” had an e ig h t digit A PI num ber in the “link_fld” field. In order to perform a tabular join a new field, called “link_fld” is added to the “G W A_Prod_W ells_BH ” f eatu re class. T h e fie ld c a lc u la t o r w a s u s e d t o s lic e t h e e x is t in g , t e n d ig it A P I num ber. Em ploying the python parser, the following script was used:
“!A PI![0 :8 ]”
This script rem oved the last two num bers, in positions “9 and 10,” from the e x is t in g “ A P I” field; creating an 8 digit A PI num ber that w ill join w ith the
“G W A _ S u rf_Loc” featu re class.
The one to one tabular join was created “GW A_Prod_W ells_BH” featu re class as the join table, while the “GW A_Surf_ L o c,” featu re class w as iden tified as th e targe t t a b le . Post join, those records with Null values in the added
“ GW A_Prod_W ells_BH” fields are assum ed to be Vertical. To select the vertical w ells, all records w ith non - null values in the
Spacing Units in the Greater W attenberg Area D illo n - 26
“GW A_Prod_W ells_BH.deviation_” field w e re selected. Then th e s e le c t io n was sw itch ed, an d the newly selected “NULL” wells were copied and pasted into the “G W A_Prod_W ells_BH” feature class.
The tabular data in the “G W A_Prod_W ells_BH” w as edited t o reduce the num ber of data fields, as w ell as later confusion. First, th e existin g
“facility_ s” field; th is field w a s n u ll if th e record refers to a direction ally or horizontally drilled w ell. Therefore, the “NULL” values were assign ed a “D D ” code, for directionally d r ille d . U s in g t h e fie ld c a lc u la t o r , “N U LL” values in
“ API_Label,” “O perator,” and “W ell_Nam e” were populated from
“attribu te _ 1 ,” “ attribu te _ 2 , ” and “attribu te _ 3 , ” respectively. A fte r th e data was pulled out of the later three fields, these non- norm alized data fie ld s were rem oved. O ther fields deleted inclu de: U TM X, U TM Y, Link_fld1_M depth, tvd, O bject_ID, KKey_API, and fa c ilit y _ t . Unfortunately, the newly com bined
API num bers did not have the sam e form at. The bottom hole locations for dire ction al w e lls do n ot con tain th e state code bu t con tain th e re com pletion code; con versely the bottom hole locations for vertical w ells include the state code bu t n ot th e re com pletion code . The directionally drilled w ells w ere selected, and using the VBScript parser in the field calculator, the state code w as added, em ploying the follow ing script:
“0 5 - ” & [API_Label]
Spacing Units in the Greater W attenberg Area D illo n - 27
The recom pletion code was rem oved by slicing the text string, using nearly the sam e m ethod as was used to create the “lin k_fld” in th e
“G W A _ Prod_ W ells_B H ” featu re class. O nce again, utilizing the python parser, th e follow ing script w as u sed:
“!A PI![0 :12]”
F ig u r e th re e , portrays the w orkflow required for creating the feature classes in the W ell Feature Dataset.
Spacing Units in the Greater W attenberg Area D illo n - 28
Surface Locations G W A_Surf_Loc (COGCC)
Bottom Locations C lip : G W A_Prod_W ells_BH (COGCC) GW A Boundary
B o tto m Locations G W A_Horiz_BH_Loc (COGCC)
D e v ia tio n S u rv e y s GW A_Horiz_W ellBore (COGCC) G W A_Prod_W ells_BH
A d d : V e rtic a l Rem ove: GW A_Horiz_W ellBore Su rfa ce Planned Locations Locations G W A_Horiz_BH_Lo c Rem ove: Locations, One- to - One Tabular Rem ove: D o m e stic W e lls, Join to: Directional Abandoned G W A_Horiz_BH_Loc W e lls Locations
W ell Feature Dataset GW A Spacing Unit Database
GW A_Horiz_W ellBore 460’ Bu ffer G W A_W B_Buff
Figure #3, W ell Feature Dataset
B u ild in g S p a c in g U n its The first step in creating spacing units for the horizontal w ells in the GW A was to apply a four hundred sixty foot buffer around each horiz o n t a l w e ll
Spacing Units in the Greater W attenberg Area D illo n - 29
stick. The 460 foot width of the buffer is determ ined by the CO G CC’s r u le
318A.a(4)C (COGCC 2013, 34).
“If a well is proposed to be located less than four hundred sixty (460) feet from the governm ental quarter- quarter section boundary, a w e llb o r e s p a c in g u nit (“w ellbore spacing unit”) for such w ell shall be com prised of the governm ental quarter- qu arte r se ction s th at are located less than four hundred sixty (460) feet from the wellbore regardless of section or qu arter section lines. “
The b u ffe r w ill b e u s e d not only to create the required spacing units, bu t also in the quality control process of verifying th ose spacing u n its. A fte r cre ation , t h is b u ffe r la y e r was added to the “W ellData” feature dataset as
“ GW A_W B _ B u ff”.
A ll q u a r t e r - qu arter section s intersecting the “GW A_W B_Buff” layer were selected from the “GW A_Q trQtr shapefile. The r e s u lt in g 2,468 quarter- qu arte r se ction s were exported out as a shapefile and n ot incorporated in t o the geodatabase, as th is is a tem porary file . T h is w o r k in g , q u a rte r- qu arte r s h a p e file w as s p a t ia lly joined, with a one to m any relationship, to the
“G W A _ W B_B u ff,” la y e r and exported as “GW A_SpacingUnits” to th e
“S p a c in g U n it ” fe atu re datase t. The one- to- m any relationship creates the required overlapping polygons required for spacing units. After which the tem porary, working file was deleted.
The resulting “GW A_SpacingUnits” s h a p e file c o n t a in s 4,263 individual polygon s to create spacing u n its for 455 horizontal w ells. The dissolve
Spacing Units in the Greater W attenberg Area D illo n - 30
function i s u sed to aggregate m ultiple polygons w ith m atching attributes into a single polygon. In this case, the “ET_ID” field, or API num ber, was used as t h e d is s o lv e fie ld . A fte r aggregation, the resulting polygon count in the new
“G W A _ S U _ D issolve” featu re class is 455. F ig u r e fo u r, b e lo w , de m on strate s the am ount of polygon overlap involved with spacing units in the GW A.
F igu re # 4 , Spacin g U n it O verlap
Spacing Units in the Greater W attenberg Area D illo n - 31
Th is figu re sh ow s a p p r o x im a t e ly t w e lv e section s in tw o tow n sh ips. W it h in th is sm all area, a total of fifty - fo u r w ells have been drilled. Determ ining whether this overlap is appropriate is the end goal of the engineer’s analysis.
The newly created spacing units now require rigorous exam in a t io n for quality con trol pu rposes. W it h so m a n y w e lls b e in g d r ille d in a s e c t io n , it is im perative th at each spacing u n it is correct. The follow ing figure fiv e sh ow s spacing unit creation guides for w e lls d r ille d w it h e it h e r n orth - sou th , east- w est, o r cate r- corn er orientations.
Spacing Units in the Greater W attenberg Area D illo n - 32
F igu re # 5 , Spacin g U n it Creation G u ides
In addition to these spacing unit guidelines, there are a num ber of other rules that must be considered when building the spacing units. A fe w o f th e m ost com m on considerations have been included. First, exploratory w ells, or
“w ildcats” can be listed as “con fidential” for a period of six m onths. T h is pe riod is inte n de d to prote ct th e ope rator from having to share information
Spacing Units in the Greater W attenberg Area D illo n - 33
w ith pote n tial com pe titors (C O G C C 2 0 0 9 , 1 ). O ne of the item s considered confidential is a w ell’s directional survey. W hen this information is m issing, a sim ple line is draw n from the surface and bottom hole, le a v in g t h e a c t u a l w e ll p a t h , a n d p o t e n t ia l s p a c in g u n it , u p to th e an alyst to de ciph e r. F ig u r e s ix , shows an exam ple of this situation, and the analyst’s interpretation.
F igu re # 6 , W e lls w ith ou t D irection al Su rveys
Spacing Units in the Greater W attenberg Area D illo n - 34
The w ells w ithout directional surveys, show n on the right, are m ost likely drilled in the sam e way as those shown to the left. Therefore a north- south spacing unit is applied, not a cate r- corn er type spacing unit.
A n oth er com m on issue occurs in the buffering and quarter- quarter selection process. Buffers are applied around the entire well bore; however a well com pletion breaks up rocks perpendicular to the well bore. Any quarter- quarter sections selected just beyond the w e llb o r e ’s TD are done so inaccurately. Furthermore, the entirety of a horizontal well bore, as shown on th e m ap, is n ot com plete d. Essentially, the w ell bore show n is som ew hat sim plified in order to render it in tw o dim ensional space. In cases w here w ell bores “d r ill out” before going horizontal, the “d r ill out” portion is not com pleted, and therefore not included in the spacing unit. To correct th ese, and other issues every spacing unit is verified and edited by the analyst. A s
S pacing U n it shapes are verified, they are cut from the
“GW A_SpacingUnits _ D is s o lv e ” fe atu re class an d paste d into th e
“G W A _ S pacingU n its_ Q C ” featu re class. F ig u r e seven, de picts th e tw o m ost com m on spacing unit issues .
Spacing Units in the Greater W attenberg Area D illo n - 35
F igu re # 7 , Buffering and Quarter- Q u arter Selection Errors
In the process of perform ing the quality ch eck of spacing u n its, a su spect w e llb o r e w as identified in section one of township two north, sixty- six w est.
Thi s w ell bore, a sidetrack, appears to be drilled w ith a different orientation than the surrounding wells. T h e o r ig in a l w e ll w a s a d d e d t o th e m a p t o v e r ify th e sidetrack’s deviation su rvey. The original w ell bore appears to be drilling a n orth - sou th traje ctory , like th e offse t w e lls. B ecause w ells are drilled to
Spacing Units in the Greater W attenberg Area D illo n - 36
leverage an area’s geology, it is likely that th e incon sisten cy is du e to an inaccurate bottom hole location. W hile an erroneous d ir e c t io n a l s u r v e y c o u ld also be at fault, the straightness of the w ell bore line indicates no directional survey exists. F ig u r e e ig h t sh ow s th e suspect w ellbore and the original w ell in addition to th e offset w ells .
F igu re # 8 , S u sp icio u s W e ll B o re s
In the interest of data integrity, these two wells were rem oved from the an alysis, leavin g a total of 4 53 t o t a l s p a c in g u n it s . The w orkflow for creating
Spacing Units in the Greater W attenberg Area D illo n - 37
the feature classes in the Spacing Unit Feature Dataset is presented in figure nine b e lo w .
G W A_Prod_W ells_BH W ell Feature Dataset GW A Spacing Unit Database G W A_W B_Buff Select b y Lo cato n : In tersectin g G W A _Q trQ tr_Sectio n s
Culture Feature Dataset G W A _Q trQ tr_Sectio n s GW A Spacing Unit W o rkin g Q trQ tr.Sh p Database
One- to - M any D isso lv e : GW A_SpacingUnit S p a tia l Jo in to : ET_ID G W A_W B_Buff
GW A_SpacingUnit_Dissolve
SpacingUnit Feature GW A_SpacingUnit_Report Quality Check Dataset GW A Spacing Unit Database
One- to - M any GW A_SpacingUnit_QC S p a tia l Jo in to : G W A_W B_Buff
F igure #9, Spacing Unit Feature Dataset T y in g S p a c in g U n its to P r o d u c in g W e lls The final step in the A rcG IS w orkflow was to tie th e produ cing w e lls to th e created spacing units. Th is task was accom plished by creating a on e- t o -
Spacing Units in the Greater W attenberg Area D illo n - 38
m any spatial join. Because the producing well locations need to be preserved for future use, the “GW A_Prod_W ells_BH” was u se d as th e targe t feature,
“GW A_SpacingUnits_QC” wa s u sed as th e join feature; and com pletely w it h in w a s selected as th e m atch option . The resulting featu re class was saved in the “W ell” feature dataset, a s “G W A_SpacingU nit_Report.” These steps are shown in the above, figure nine, workflow diagram .
Preparing the Table for delivery The “G W A _ S pacingU n it_ R eport” featu re class includes a database table th at needs to be exported and m anipulated to be suitable fo r Narayan’s u se.
A fte r ex porting th e tabu lar data as a database file, it was resaved as an
Excel workbook. A ll the colum ns, except ET_ID and API_ L a b e l were rem oved. For th e an alysis, th ese colum n s are m eaningless to th e engineer; deleted colum ns include: ObjectID, Join_Count, O perator, W ellNam e,
TARG ET_FID, JO IN_FID, linkfld, facility_s, Lat_NAD83, LONG_NAD83. The rem aining colum ns were renam ed; “API” was changed to “ P r o d u c in g W e ll,” and ET_ID was renam ed “ S p a c in g U n it .”
The next data m an ipu lation task w as to corre ct th e producing w ell records.
In the original data table, API num bers in the “ A P I” fie ld c o n t a in d a s h e s .
Because these API num bers are used to acquire production data fro m a vendor, whose system doesn’t recognize dash es, th e y were rem oved.
A dditionally, an “0 5 - ” is added to th e API num bers in the “ S p a c in g U n it ” colum n for the benefit of the engineer.
Spacing Units in the Greater W attenberg Area D illo n - 39
A fter the identifying num bers were corrected, som e basic tabular editing was perform ed. B ecause a w ell’s ow n production w ill skew the analysis, its production record m ust be rem oved from its spacing unit record. M any spacing units do not contain any other producing wells, and are therefore rem oved from the workbook. The follow ing table th re e sh ow s a sam ple pulled from the Spacing U nit Report.
T a b le # 3 , Layers & Sou rces Producing Spacing U nit W e lls 05- 123- 1512500 0512322285 05- 123- 1959700 0512334277 0512334288 05 - 123- 2270800 0512322706 0512322681 0512322680 0512322709 0512331647 0512331666 05 - 123- 2270900 0512322706 0512322681 0512322680 0512322708 0512331647 0512331666
A fte r tabu lar e diting, th e re are a total of 395 spacing units containing p r o d u c in g w e lls . The resulting table w as delivered to N arayan for his a n a ly s is .
Spacing Units in the Greater W attenberg Area D illo n - 40
R esu lts The w orkflow described h erein w as su ccessful in creating accu rate spacing u n its to assess th e econ om ic feasibility of drillin g h orizon tal wells in th e
GWA. U t iliz in g A rcG IS , resu lts w ere produced m uch sooner than if the analysis were done com pletely by hand or by using another software.
D iscussion By taking full advantage of softw are and em ployees’ skills, a com pany is m ore nim ble. In th is case, by le v e r a g in g ArcGIS’ geoprocessing tools; spacing units, producing w ells, and a final report w ere produced quickly. The relatively short am ount of tim e required to pr o v id e th e fin a l r e p o r t a llo w e d the engineering team am ple time to assess the data. A well thought out assessm en t lead to a deliberate conclusion which reduces t h e r is k o f m a k in g a h asty d e c is io n .
By using ArcGIS, a large am ount of th e an alyst’s tim e is saved. A rcG IS h as a num ber of built in functionalities that allow for a certain am ount of autom ation in th e process of bu ilding spacing u n its. Unfortunately, if spacing units were created in Petra, not only would each unit need to be drawn by hand, but the deliverable spreadsheet w ould have to be populated by hand as w ell. It is estim ated that using ArcG IS c u ts th e am ou n t of tim e to com plete the project in half. This t im e savings equ ates to a sizeable, t a n g ib le b e n e fit t o the com pany, increased c a p it a l e ffic ie n c y . Doing m ore with less frees up capital to spend on other projects or other needed staff. If
Spacing Units in the Greater W attenberg Area D illo n - 41
t h is workflow were applied to assets in oth er bu siness u n its, th e c a p it a l efficiency is sure to increase, perhaps exponentially.
A d d it io n a lly , th e su ccessful com pletion of th is an alysis de m on strate s th e value of A rcG IS in the oil and gas w orkflow . W h ile there are a num ber of petroleum specific software packages on the m arket, th e re isn ’t on e th at su ccessfully com bines su rface m apping an d an alysis with subsu rface m apping and analysis. Because shapefiles are a geospatial standard, data is easily transferred between software packages, allow ing A rcG IS to fill t h is niche in the industry.
Areas for Further Research This project leaves m uch opportunity for further research. Continuous m o n it o r in g is b e in g c o n s id e r e d fo r th e G W A a r e a . If it is decided th at continuous m onitoring is in fa c t necessary, it w ill be essential to autom ate a s m uch of th e data cre ation proce ss as possible. M any, if n ot all, of th e required ste ps, save th e qu ality con trol ch ecks, can be accom plished w ith a m o d e l. The creation of a m odel w ill save the analyst a great deal of tim e; produ cing resu lts m ore q u ic k ly a n d accu rately.
M o r e p o t e n t ia l for further research exists in reducing the need for q u a lit y control of spacing u n its. Results could be produced m ore quickly if t h is portion of the w orkflow could be abridged. O f cou rse, th is m ean s creatin g m ore accu rate spacing u n its on th e first pass. A num ber of opportunities
Spacing Units in the Greater W attenberg Area D illo n - 42
exist to potentially accom plish this goal, including m odifying the w ell deviation surveys, revising the buffering technique, or changing the quarter- quarter selection techniques.
The m ethodology described herein c o u ld e a s ily be m odified to apply to another field or play. F orm ation properties, such as porosity an d perm eability, vary between reservoir rocks. These incon sisten cies influen ce spacing u n its across th e cou n try. In order to properly apply this m ethodology the buffering distance w ill require m odification depending on the specific spacing unit regulations. Furtherm ore, this m ethodology could be applied to direction ally or vertically drilled w ells, so lon g as spacin g regulations are honored.
Spacing Units in the Greater W attenberg Area D illo n - 43
G lossary of T erm s D ir e c t io n a l S u r v e y - M easurem ent of a w e lls ’ inclination ( d e v ia t io n fr o m v e r t ic a l) and azimuth (com pass h eading) o f a w e ll bore.
P la y - An area in which hydrocarbon accum ulations or prospects of a given type occu r.
O ffse t- E x is t in g w e llb o r e s c lo s e t o a proposed, or drillin g w ell, th at prov ide information for planning purposes.
W ild c a t - A n exploratory w ell, a w ell drilled in a new area w ith few , or no, o ffs e t t in g w e lls .
Spacing Units in the Greater W attenberg Area D illo n - 44
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