A NEW MATERIAL for DEEP WELL CEMENTING Downloaded from http://onepetro.org/trans/article-pdf/207/01/59/2176783/spe-508-g.pdf by guest on 02 October 2021

DWIGHT K. SMITH HALLIBURTON OIL WELL CEMENTING CO. MEMBER AIME DUNCAN, OKLA.

T. P. 4222

ABSTRACT Economically speaking, this composition is less expen­ sive than either portland cements or retarded cements A new pozzolanic composition has been developed for presently being used under deep well conditions. cementing oil wells where moderate to high tempera­ tures prevail. This material is an entirely different con­ cept to other oil well cementing materials, such as INTRODUCTION portland cements, cements containing additives, or liquid Pozzolans are "siliceous material which, though not resins. Its characteristics are such that it is not, at pres­ cementitious in themselves, contain constituents which ent, recommended for use at temperatures less than at ordinary temperatures will combine with lime in the 140 0 F. It can be either accelerated or retarded across presence of water to form compounds which have a low a wide range of well conditions. solubility and possess cementing properties.'" The use of This new cement is composed of a pozzolanic ma­ pozzolanic materials dates back many hundreds of years terial, hydrated lime, and a chemical activator to give and both the ancient Greeks and Romans were aware it early initial strength. This material can be used in that certain volcanic deposits, if finely ground and mixed wells from 6,000 to 18,000 or more feet where tempera­ with lime and sand, yielded a mortar which possessed ture conditions are similar to those along the Gulf special properties.' Generally, the early strengths of such Coast. This cement, when set, has no soluble portion materials were rather weak and were considered insuf­ subject to leaching or any compounds that should be ficient for modern commercial usages. attacked by sulfate waters or brines. For this reason, it Pozzolanic materials have been used extensively with should be permanent when placed adjacent to forma­ portland cement in mass concrete to obtain special tions carrying any type of fluid. properties. In recent years, large quantities of certain The compressive strengths in 24 hours are more than 0 pozzolanic materials have been used successfully ad­ adequate for wells where temperatures are 140 F and mixed into portland cements for oil well cementing. higher. These values are in excess of many other types Pozzolans, being reactive silicates, will combine with of cementing composition presently in use in the field. the free lime that is an inherent component of set port­ This pozzolanic composition does not retrogress in land cements and thereby, becomes cementitious them­ strength at high temperatures as do some other types of selves. cementing materials. The slurry weights of this material will vary slightly according to the specific gravity and water requirements POZZOLANS FOR OIL WELL CEMENTING of the pozzolan itself. The materials covered herein will There are many types of pozzolans, some of which mix from 13.5 to 14.3 lbl gal, and will have a waiting­ are more reactive than others. The quality of the pozzo­ on-cement time comparable to other materials used under the same conditions. Ian depends on the degree of reactivity, chemical com­ position, fineness, and other less well understood factors. Original manuscript received in Petroleum Branch office on Aug. 30, Some of the more widely accepted pozzolans are those 1955. Revised manuscript received on Feb. 9, 1956. Paper presented at classified as fly ashes, while others are certain materials Petroleum Branch Fall Meeting in New Orleans, Oct. 2-5, 1955. Discussion of this and all following technical papers is invited. of volcanic origin. Pozzolans which require large vol- Discussion in writing (3 copies) may be sent to the offices of the Journal of Petroleum Technology. Any discussion offered after Dec. 31, 19i6, should be in the form of a new paper. lReferences given at end of paper. SPE 508-G VOL. 207, 1956 59 umes of water to produce pumpable slurries are gen­ PORTLAND CEMENT _. - . - . - . - erally unsatisfactory. This paper will deal principally POZZOLAN-PORTLAND CEMENT --- - I-- with those pozzolans commonly called fly ashes. POZZOLAN LIME Fly ash is the combustion product resulting from the !z ~ 16-0 burning of pulverized coal in steam generating plants. a: IIJ 'A~ After burning, the ash is collected on electrical or me­ a.. ..,-:; : .-;;; 180' F -;:-...... - chanical precipitators in the form of a grey powdery I 12.0 IIJ substance having a high degree of fineness. Fig. 1 is 2: :J a photomicrograph illustrating the physical appearance IIJ 8.0 of fly ash when magnified 250 times. As shown, most of IIJa: u. the particles are spherical in shape. These round parti­ 1-- ..... 4.0 cles function as tiny ball bearings producing a slurry t- having low friction loss during displacement. A typical -- ,- I- .- l- .- 140- i-- analysis of a good quality fly ash is as follows: --~F -- I-- t-- ,- I- 180-F o -- - 0 -- 4 8 12 16 !O :4 ~ Per cent Silicon Dioxide ___ "______.. _._. _____ ._._ . ____ 40.54 CURING TIME - DAYS Aluminum Oxide ______18.51 I ron Oxide ______23.19 FIG. 2 - FREE LIME CONTENT. Magnesium Oxide ______.. ____ 1.05 Calcium Oxide _ _ 6.31 Sulphur Trioxide .. ___ . ______.. ____ 1.55 Loss on Ignition. __ ___ ._ 2.76 CHEMICAL AND PHYSICAL PROPERTIES Sieve Analysis Passing 200 mesh sieve.______. __ 98.2 The compounds formed in the chemical reaction of Downloaded from http://onepetro.org/trans/article-pdf/207/01/59/2176783/spe-508-g.pdf by guest on 02 October 2021 Passing 325 mesh sieve. ___ .. ______... ______... ____ 93.8 these materials when mixed with water are not yet com­ Surface Area (Blaine) - Square centimeters per gram ______" 3,062 pletely understood. Fig. 2 shows the free lime content of set portland From a study of literature, it is inferred that the cement (ASTM Type I), a pozzolan-portland cement "reaction products which contain the reactive silica of mixture, and pozzolan-lime composition at various times the material may be either the hydrated calcium silicate to 28 days. Laboratory investigations reveal that hy­ or the hydrated silico-aluminate, whereas the alumina drated lime added to pozzolans combines very rapidly containing products may be either the tetracalcium alu­ under the recommended conditions, and after 24 hours minate-hydrate or the silico-aluminate.'" there is only very slight evidence of any free lime re­ Due to the complex nature of the chemistry of cal­ maining. X-ray diffraction studies confirm these chemi­ cium-alumino-silicate of cements, no attempt will be cal behaviors of pozzolan and lime as well as that of made at this time to explain the exact chemical behavior portland cement. of this new cementing composition. Pozzolan-lime slurries used above ground have a dis­ An extensive study has been made on the physical advantage in that hardening is slow at atmospheric tem­ behavior of this cement under various well conditions. perature and pressure. This disadvantage is eliminated in An investigation of various sources of this material re­ the cementing of oil wells where extended pumping time veals that some fly ashes are more reactive and have is desirable and where the accelerating effects of high properties which produce products that are equal or temperature and pressure promote early hardening of superior to many cements in common use. Continual such mixtures once in place in the well. Considerable analysis of fly ash from a given plant over a period of investigation revealed that this reaction can be activated months indicates that the material is very uniform in its with small amounts of various chemicals to produce a cementitious material that has satisfactory strengths in chemical and physical behavior. 0 24 hours at temperatures as low as 140 F. When mixed MIXING AND BLENDING OF MATERIALS with the proper amount of activator or retarder, these The pozzolan-lime materials are handled through con­ materials can be controlled to allow adequ~te placement ventional bulk cement stations where these components time in wells from 6,000 to 18,000 or more feet in depth where temperatures are comparable to those are uniformly blended in a batch type bulk plant as illus­ shown in Table 1. trated in Fig. 3. In this type of system the components are individually weighed into a mechanical blendor where they are intimately and uniformly mixed into a homogenous blend. Small amounts of retarder can be accurately proportioned and properly blended in these systems. This techniques of proportioning and blending makes possible the formulation of specific compositions to meet any requirements of well depths and tempera­ tures. Transportation to the well and mixing on location are handled in much the same way as any other ma­ terial.

TABLE 1 - AVERAGE TEMPERATURE GRADIENT FOR GULF COAST*

Well Bottom Hole Temperature 0 F Mud Discharge Depth Static Circulating Temperature 0 F 4,000 140 103 100 6,000 170 113 108 8,000 200 125 118 10,000 230 144 130 12,000 260 172 146 14,000 290 206 168 16,000 320 248 199 18,000 350 300 240 *Oota from study made by API Special Subcommittee on Oil Well Cements.

60 PETROLEUM TRANSACTIONS, AIME TABLE 3 - POZZOLAN·LlME COMPOSITION Per cent Well Static Thickening Time Retarder Depth Temperature OF Hours:Minutes 0.3 16,000 320 2,02 0.5 16,000 320 2,31 0.75 16,000 320 2,58 1.00 16,000 320 3,40 1.50 16,000 320 4,59 2.00 16,000 320 3,47* 2.00 16,000 320 3,21 ** 1.50 18,000 350 2,36 2.00 18,000 350 3,56 *Slurry weighted to 17.5 Ib/gal with barium sulfate. **Slurry weighted to 19.0 lb/gal with barium sulfate.

being principally due to the specific gravity of fly ash SCALES as compared to cement. Thus a lighter weight slurry is obtained without using special additives such as benton­ FIG. 3 - MECHANICAL BLENDER. ite and water. This reduction of slurry density results in lower pump pressure while displacing and increased fill SLURRY PROPERTIES up of cement between the casing and formation for The physical characteristics of pozzolan-lime slurries a given hydrostatic pressure. were evaluated by techniques and procedures outlined Where heavier slurries are required, the weight can be in API RP lOB, "Recommended Practices for Testing increased by the use of barium sulfate or other high Downloaded from http://onepetro.org/trans/article-pdf/207/01/59/2176783/spe-508-g.pdf by guest on 02 October 2021 Oil Well Cements." It can be observed from typical density weighting materials. values shown in Table 2 that these compositions require approximately the same mixing water requirements as STRENGTHS conventional cements; however, due to differences in The accepted criteria of strengths for oil well cements specific gravities, they will weigh somewhat less. A sack will vary with operators and localities. Earlier investi­ of dry material will weigh 74 lb without additives, and gators,,5 have found that high strength cements are not will have an absolute volume of 3.6 gal, the same as necessary; consequently, many operators consider 500 portland cement. psi satisfactory before resuming rig operations. When used under temperatures greater than 140 0 F, TABLE 2 - SLURRY PROPERTIES Retarded these pozzolanic compositions have strengths that are Pozzolan Cement more than adequate and meet specified requirements set Weight, pounds per sack .. __ _ 74 94 Water, gallons per sack 4.5 - 5.0 4.5 - 5.4 forth for oil well cements. Slurry weight, Ib/gaL~~ ~ 13.8 -14.3 15.5 -16.3 At temperatures less than 140 0 F the compressive and Slurry volume, cu ft per sack 1.12-1.21 1.07·1.20 tensile strengths are very low in 24 hours, but later will THICKENING TIMES set hard and can be used if early strength is not con­ Laboratory evaluations of the fluidity of pozzolan­ sidered significant. Typical strength values under various lime slurries were determined on the Stanolind high temperatures are shown in Fig. 7. The values on speci­ pressures thickening time tester which simulates tem­ mens cured at temperatures less than 2000 F were under peratures and pressures actually encountered when ce­ atmospheric pressure. Corresponding slurries cured menting wells. Typical values for thickening times under under pressure should produce greater strengths. All well depths ranging from 6,000 to 16,000 ft are given slurries cured at temperatures above 200 0 F were under in Figs. 4 and 5. These values are shown with varying 3,000 psi pressure and contained a chemical retarder. In percentages of a lignin-type retarder. It would be advis­ Fig. 8 comparative strength values are illustrated under able to use chemical retarders in wells where static tem­ curing conditions up to seven days at 140 0 F. peratures exceed 230°F (approximately 10,000 ft Previous studies on strengths of cements under high depths) to insure adequate placement time. It should be temperatures' show that retrogression occurs at tempera­ noted that all values without retarder have ample fluid­ tures above 220 0 F in many types of cements. Investiga­ ity under 2300 F to give thickening times of three hours tions of this phenomena are given in Fig. 9, which shows or more. Fig. 5 and Table 3 indicate that the pozzolan­ values of this new cementing material under different lime composition can be successfully retarded to meet temperature conditions. Data obtained at 220 0 F and API specifications for deep well cements. Comparative 268 0 F reveal no serious evidence of strength retrogres­ values for different retarded cements are shown in sion up to a curing time of 28 days. Fig. 6. 100 For well conditions beyond 14,000 ft, laboratory data (/) w reveals the possibility of formulating blends of pozzolan­ (/) J lime cement to allow longer pump ability than presently ~ AC I~ ~ I possible with conventional retarded cements. These >­ ~I gJ. f- values for 16,000 and 18,000 ft well conditions are en 60 / shown in Table 3. 8 (/) / 10 bo ;;: V SLURRY DENSITY >- 0 / 0:: 0:: / In recent years considerable emphasis has been placed ::J -' ./' ../ f- -- ~F on light weight cementing compositions. Low density (/) 2 0 -- - -- ~ slurries are certainly an advantage in those areas where - formations will not support heavy cement columns. In 0 many instances, there is a possibility of losing circulation I 4 in zones being cemented if neat portland cement is used. THICKENING TIME -HOURS Pozzolan-lime slurries will mix at approximately FIG. 4 - THICKENING TIMES, POZZOLAN-LIME CEMENT 2 lb/gallighter than regular neat cement. This difference WITH No RETARDER.

VOL. 207, 1956 61 '6 l!\ The waltmg on cement time is dependent on many I­ 1\ factors, yet strength of the cement is considered the ILl ILl \ ... 4 :" most significant. As previously mentioned, this material R I"\. '" "1"-.. develops adequate strength in a minimum time which o ""'" I"'-- allows WOC times consistent with other cements and 2 f"'- J"-.- ~, ...... admixtures under the same conditions. Field experience ~I 1'--.. I"--- 1'--t- .5 RE ARO ER X " "" to date has proven that pozzolan-lime compositions do ...... t- :I: ,0 ~I I'--.. 1'-- .3 RE RO R not require additional waiting time at temperatures Ii: t-- ILl => t- .0 RE RO R above 140° F. o '" ~I ~ 8 SLURRY COST ~ ILl ,:;= ~: Cementing costs will vary with locality and cementing 6 , I compositions. The cost per sack of the pozzolan-lime is 0 2 3 4 5 6 7 considerably less than retarded cements which would be TH ICKENING TIME - HOURS used under the same conditions. Since pozzolan-lime FIG. 5 - THICKENING TIME, POZZOLAN-LIME CEMENT. slurries have properties which are superior to other materials, they should be more desirable for deep well cementing.

'6 I­ EFFECT OF ADDITIVES ILl II ~ ILl ... ,,~ The use of weight reducing additives such as benton­ Downloaded from http://onepetro.org/trans/article-pdf/207/01/59/2176783/spe-508-g.pdf by guest on 02 October 2021 • '4 o ite, perlite, etc. are not recommended in this composi­ o Ii ~ ~ o tion since they require large volumes of water and will ~ x '2 11 k'\ reduce the strength of the set mass. A low water ratio :I: I~ \' ~ material will produce a more dense slurry having lower ~r ...... Ii: '0 ,\ ~ t---.. permeability when set. Measurements have been made ~ 1 ...... poz OlA -LI E 5 !\ \ ~ "- 0.5 RE ARD R) on permeabilities of pozzolan-lime slurries set under :l ~I various conditions, and the values obtained were found ILl 8 f"-. " to be in, or below, the normal range expected for port­ == ~I \ \ ""'- GEM NT' ;r- GE" NT "e" land cement. 6 I ~ iPoR lAN GE ENT "s" 0 , 2 3 4 6 There are occasions in which a heavy weight slurry THICKENING ""TIME -HOURS may be desired in deep wells to control high pressure FIG. 6 - THICKENING TIME, VARIOUS CEMENTITIOUS gas zones. Laboratory data show that certain weighting MATERIALS. materials can be added to this composition for this pur­ pose as shown in Table 4.

TABLE 4 - PROPERTIES OF POZZOLAN-LIME CONTAINING BARIUM SULFATE. Barium Sulfate Slurry Weight Slurry Volume Waler f- 3~ ~ :1SYS f-- Ib Ib/gal cu It/sack gal/sack :z: V 14.40 1.17 4:55 l­ 4 V ~ - 10 15.00 1.20 4.74 t!) V V- 'OY Z _ ./~ V 35 16.00 1.38 5.40 UJf/) 65 17.00 1.57 6.02 a: 0.. I I- , / V V 100 18.00 1.78 6.61 f/) 0 II \/V EFFECT OF SEA WATER FOR MIXING ~ ~ f/) 2 / / Ii 3000 PS, RES UR Many times for convenience or of necessity, it is f/) x 0.3 RE ARC R UJ / desired to mix cement with Gulf water during offshore , / drilling operations. Such sea waters contain soluble salts I f-- .-~- r- . - AP R QUr EM'" 'rs- lA S o Ato -rOE 'EN which will accelerate the thickening time of pozzolan­ V lime slurries and should not be used without prior test­ o '20 '60 200 240 280 ing during the completion of deep wells. In wells where TEMPERATURE -OF static temperatures from 140° to 230°F prevail, it is very FIG. 7 - COMPRESSIVE STRENGTH, POZZOLAN-LIME possible to use Gulf water instead of fresh water. CEMENT. This will, in effect, shorten the setting time and pro­ duce a stronger cement at an early age at low tempera­ tures. The comparative effect of Gulf brine on this cement is shown in Table 5. PO OL N-l 'ME 4 +- ~ 4 .. lo.FI IGEM NT FIELD RESULTS

3 V l?' This new oil well cementing composition has been used in a number of wells in different areas at depths s'!, GEL IcEM NT 2 V I-- exceeding 6,000 ft. The mixing and handling of this f/ ~ ~ V 12% GEL GEM NT material under field conditions have not varied from , Iii ./ I-- conventional cementing operations. h V V l- The WOC times have been comparable to normal ~ o 4 6 practices for a given location and temperature surveys CURING TIME - DAYS indicate no abnormal change in the time element for FIG. 8 - STRENGTH COMPARISONS, PORTLAND CEMENT locating the top of the cement. WITH BENTONITE 140° F. The heat liberated during the setting of the pozzolan-

62 PETROLEUM TRANSACTIONS, AIME TABLE 5 - EFFECT OF GULF BRINE ON POZZOlAN CEMENT. Thickening Time - Hours:Minutes Simulated Well Depths 8 10,000 12,000 14,000 :I: ~ Fresh Water...... "...... 4,45 2,56 ~ C) Gulf Water...... _...... 2,28 2,20 1 dO Z II 261 OF Compressive Strength - psi ....~- (f) Curing Time Fresh Water Gulf Water (f)Q. ., ~ 22< F Days 140" F 180" F 140" F 1800 F ~ • 4 1 1,420 3,350 2,255 2,665 ~§ r-. r-. 260 F 3 3,410 4,285 4,100 3,650 (f)- - 7 4,070 3,934 4,335 3,925 X \RET ROE CE~EN "0" :3 2 0: Q. lime composition is somewhat less than regular cement 8 o but is sufficient to locate the cementing top. o 4 8 12 16 20 24 28 On these jobs the wells have been completed either by CURING TIME - DAYS perforating and/or fracturing and show no evidence of FIG. 9 - STRENGTH RETROGRESSION, POZZOLAN-LIME. communication or channeling behind the pipe. It has been observed that pozzolanic compositions differ from other cementing materials in that they do of other additives. These slurry weights can be increased not possess high gelling properties upon setting. When by the use of special weighting materials to a density of allowed to set static for short periods of time portland 19 Ib/gal and still provide good pump ability and cements will gel rapidly and require high pressure for strengths upon setting. Downloaded from http://onepetro.org/trans/article-pdf/207/01/59/2176783/spe-508-g.pdf by guest on 02 October 2021 movement. Pozzolan-lime compositions have been found 6. Displacement pressures are normally lower due to to possess very low gelling properties upon setting and its spherical shape composition which results in low fric­ can be moved with much lower pressures after stand­ tion loss. It does not possess a high degree of thixot­ ing. ropy which would cause the slurry to gel when allowed The lower pressures encountered while pumping or to remain static for short periods of time. displacing pozzolanic materials are due to a combination of the lighter slurry weights and the characteristic of ACKNOWLEDGMENT the spherical particles which function as tiny ball bear­ The author of this paper wishes to express his appre­ ings in the slurry. ciation to those in the Halliburton organization who In summary, the performance of this cementing com­ helped obtain data and offered suggestions for the position under actual field conditions has been very preparation of this paper. Appreciation is also extended satisfactory and does not appear to be abnormal in any to the Halliburton Oil Well Cementing Co. for permis­ respect as to handling, mixing or in well completion sion to prepare and publish this paper. practices. REFERENCES CONCLUSIONS 1. Lea, F. M., and Desch, C. H,: "The Chemistry of 1. The results of laboratory and field tests on pozzo­ Cement and Concrete," Edward Arnold & Co., lan-lime compositions show that they can be used from London (1935) Chapter XIII. 6,000 ft or deeper in wells where temperature conditions 2. Ibid., Chapter 1. are comparable to those along the Gulf Coast. 3. Turriziani, Renato, La Riceica Scientific a, "The Re­ 2. This material has been found to be uniform in its sults of Reaction of Calcium Hydrates with Pozzo­ chemical and physical behavior and meets or exceeds lans," (Aug., 1954) 1717. specifications for thickening time and strength for deep 4. Farris, R. F.: "Method for Determining Minimum well cements. Waiting on Cement Time," Trans. AIME (1946) 3. Pozzolanic-lime materials are readily available and 165, 175. can be formulated in field distribution plants to meet 5. Saunders, C. D., and Nussbaumer, F. W.: "Trends specific well requirements of depth and temperature. in Oil Well Cementing Materials," Oil and Gas Jour .. 4. This material is very economical and is appreci­ (in 3 parts) June, July, Aug., 1952. ably cheaper than many of the other cements when used 6. Saunders, C. D., and Walker, W. A.: "Strength of under the same conditions. Oil Well Cements and Additives Under High Tem­ 5. Pozzolan-lime slurries will weigh from 13.5 to 14.3 perature Well Conditions," AIME Fall Meeting, San Ib/gal and offer a lighter weight slurry without the use Antonio, Tex. (1954).

DISCUSSION

CITIES SERVICE OIL CO. D. W. HOLLAND LINDSAY, OKLA.

The author is to be commended for his development in different areas. Cities Service operations employing work and presentation of this new deep well cementing this material in the Lindsay, Okla., area, to date material. have numbered five. Depth of operations has varied In his paper he has stated this new pozzolan-lime from 8,650 ft to below 13,000 ft with correspomding material has been successfully used a number of times BHT of 150 0 and 205 0 respectively. As indicated by

VOL. 207, 1956 63 these field operations, this experimental cementing ma­ zone substantuated the fact that this 8,500 psi was im­ terial is a working substitute for regular and retarded posed against the cementing material and sand face. oil well cements in the Lindsay area. Of the five Cities Service cementing operations per­ Briefly one such operation which substantuates this formed to date using this new cementing material, only thinking consisted of successfully cementing 10,300 ft of one has given any indication of being unsuccessful. Dur­ 5V2 -in. casing in two stages, using accepted stage ce­ ring this operation 1,900 sacks of cementing material menting equipment and procedures. During mixing and were mixed, pumped and displaced in two stages, with pumping operations no abnormalities or deviation from no returns on either stage. It is felt that due to this normal cementing operations for this area were ob­ severe lost circulation, and the fact that the well started served. Displacement pressures were comparable to to flow back behind the pipe for 18 hours after cement­ operations using regular portland cement. Cement top ing operations had terminated, indicating agitation in the was located by temperature survey indicating a fill-up wellbore, the cementing material was not given ade­ of 41.2 per cent, which is considered competitive to quate opportunity to set. regular oil well cements in this area. Two upper produc­ Another major operator in this area has used this tive sand bodies separated by 107 ft were individually material on four occasions and has had repeated satis­ perforated, tested and hydraulic fracture treated with no factory performance. indication of channeling or communication, even though Although this material has been used only a short surface recorded maximum treating pressures were 5,400 time in the Lindsay area, no indications have been ob­ and 6,500 psi. served that this material is not permanent in nature. To date, the most strenuous test for this material con­ In view of the presently existing cement shortage, a sisted of perforating a low permeability sand zone and known and tested substitute for conventional oil well Downloaded from http://onepetro.org/trans/article-pdf/207/01/59/2176783/spe-508-g.pdf by guest on 02 October 2021 unsuccessfully attempting to break down the zone with cementing material is considered a worthwhile contribu­ maximum pressures of 8,500 psi. Re-perforating this tion to the oil and gas industry.

DISCUSSION

THE CALIFORNIA CO. LEWIS CREWS NEW ORLEANS, LA.

Our company is interested in pozzolan-lime cement ing is standard practice. Squeeze was obtained on the and has completed one trial run. The cement handled first try. The well came in clean and has produced clean normally in every respect for cementation, and the well since then. At present the well is being watched for a behaved normally for completion and since completed while before making another run. in the middle of July, 1955. The only advantages of pozzolan-lime cement ex­ The well was a 9,100 ft deviated hole in Dixon Bay hibited here were in the lower pump pressure required field about 10 miles south of Venice, La. The string to pump the plug down, and in the cement bill which was 7 in. in 9% -in. hole drilled with an ll-lb oil was 20 per cent lower. Also the lower slurry weight was emulsion mud. Kick-off point was 5,333 ft. Deviation present and may have helped prevent cement loss to was 20 0 and bottom hole temperature was 176°P. The the formation. No rig time was saved or lost. operation used 55 centralizers in a varied pattern from We hope the other advantages of pozzolan-lime ce­ 200 ft above the kick-off point to shoe. The string was ment over competitive materials indicated by labora­ run to bottom, picked up 1 ft and left right there. Mud tory tests will be field proven because they would help was circulated 1 Vz hours before cementing with 800 us in our operations. Especially it would be a great sacks pozzolan-lime cement using two plugs. The casing convenience to be able to use sea water for cementing. ran free and circulation was good throughout the job. At present the only criticism we have of pozzolan-lime Plug was bumped with 1,600 lb. A 1 ft interval 10 ft cement is that, to our knowledge, it has not been field below the production interval was perforated and tested sufficiently to permit adoption with complete squeezed with 150 sacks slo-set cement. This squeez- confidence. ***

64 PETROLEUM TRANSACTIONS, AIME