Hydraulic Fracturing Drilling the Well Protecting Ground Water

Bob L. Herd Department of Petroleum Engineering Texas Tech University

The New York Times. (2011, Feb. 26). [Interactive graphic hydraulic fracturing]. Extracting natural gas from rock. Retrieved from http://www.nytimes.com/interactive/2011/02/27/us/Hydraulic Fracturinging.html?_r=0 Definitions and Key Words: The Completed Well

Wellbore: the hole drilled by the bit, also Conductor called a borehole. 16” Casing: a wellbore may have carbon steel casing (pipe) in it or it may be open Surface (uncased); or part of it may be cased, 8-5/8” and part of it may be open. If it is cased it is usually cemented (more than 99% of the time). Has screwed connections Tubing: production conduit for fluids from Tubing formation to surface 2-7/8” Packer: isolates tubing and production fluids from casing Perforations/Perfs: holes shot through the Perfs Production casing and cement out into the 5-1/2” formation rock Halliburton. (2006). [Graphic wellbore]. eRedbook Wellbore. Retrieved from http://www.halliburton.com/public/news/source_files/images/bio/eRedbook_ab.jpg Occupational Safety & Health Administration. (2001). Oil and gas well drilling and servicing eTool: Glossary of terms. Retrieved from https://www.osha.gov/SLTC/etools/oilandgas/glossary_of_terms/glossary_of_terms_w.html Completing the Well: Perforating, Stimulation and Equipping for Production Definitions and Key Words

Drilling Mud: a specially compounded liquid circulated through the wellbore during rotary drilling operations, also called drilling fluid. Serves to cool the bit and counteract downhole formation pressure.

Occupational Safety & Health Administration. (2001). Oil and gas well drilling and servicing eTool: Glossary of terms. Retrieved from https://www.osha.gov/SLTC/etools/oilandgas/glossary_of_terms/glossary_of_terms_d.html Baker Hughes, Inc. (2013). [Graphic drilling mud]. NEXT-DRILL drilling fluid system. Retrieved from http://www.bakerhughes.com/products-and-services/drilling/drilling- fluids/emulsion-fluids/next-drill-drilling-fluid-system Definitions and Key Words

Hydraulic Fracturing Fluid (Frac Fluid):

Associated Press. (2011, June 20). [Graphic frac fluid]. Texas becomes first state to require frac fluid disclosure. Retrieved from http://fuelfix.com/blog/2011/06/20/texas- becomes-first-state-to-require-frac-fluid-disclosure/ Groundwater Protection Council. (2013). [Graphic frac fluid composition]. Average hydraulic fracturing fluid composition for US shale plays. Retrieved from http://fracfocus.org/water-protection/drilling-usage Definitions and Key Words

Chesapeake’s Hydraulic Fracturing Fluid:

Chesapeake Energy. (2013). [Graphic hydraulic fracturing fluid]. Hydraulic fracturing fluid. Retrieved from http://www.chk.com/Operations/Process/Hydraulic- Fracturing/Pages/Hydraulic-Fracturing-Fluid.aspx What is “Hydraulic Fracturing”?

- The use of fluids (hydraulic pressure) to create a crack (fracture) in the Reservoir Rock. - Continued injection of fluids into the created crack (fracture) to create fracture geometry (height, width, and length). - The placement of granular solids (prop) into the crack to insure the crack remains open (propped) after the hydraulic pressure is no longer being applied

Horizontal Well Hydraulic Fracturing Procedure

Horizontal borehole is drilled, cased and cemented

First completion stage: wellbore is perforated over a selected interval based on petrophysics and other data

The previously perforated interval is hydraulicly fractured by pumping fluids (usually viscous liquids) which creates cracks. Many times these cracks are pre-existing

Proppant, sand or stronger material such as bauxite, is added to the hydraulic fluid during the pumping process and enters into the previously created cracks (continuous process)

The pumps are shut down and plug is set just behind the interval just hydraulically fracture treated and the process is repeated over and over progressively back toward the heel or beginning of the horizontal wellbore, until the entire horizontal wellbore is treated

Side View

KOP Hydraulic Fracture

HMAX HMAX D

Lf Objective Formation

HMIN How the Hydraulic Fracturing Works

Proppant, sand or stronger material such as bauxite, keeps the crack open to allow gas or fluid to flow with less resistance

Bedding Planes

Proppant

Cored Hydraulic Fracture Mapping a Fracture Other Geometries Based on Actual Hydraulic Fractures Mined Several Months after Well Treatment Shale Plays

Energy Information Administration. (2011). [World map shale gas resources]. World shale gas resources. Retrieved from http://geology.com/energy/world-shale-gas/ Shale Plays

http://www.eia.gov/oil_gas/rpd/shale_gas.pdf