By Petroleum Technology Transfer Council

Using the online world to become informed on hydraulic fracturing

Many hydraulic fracturing resources are available online to industry professionals.

Lance Cole, National Project Manager, Petroleum Technology Transfer Council, Sand Springs, Okla.

Readers get a change of pace this month, as this Petroleum Technology Digest (PTD ) is more like a column than a case study. As the Petroleum Technology Transfer Council’s (PTTC’s) national project manager, I frequently listen to discussions within our regional advisory groups. A recent conversation on hydraulic fracturing raised many questions, which led me to think, “Just what could I learn online in a few hours?” Well, I found plenty within two to three hours of searching/ skimming/ reading (but don’t try this without high-speed Internet access).

PTTC. For PTTC, case studies, newsletters and workshops are key tools. Case studies are often presented in workshops, and the Petroleum Technology Digest (PTD ) has a case study focus. Upon invitation, we develop articles for trade journals, and our monthly Tech Connections column in American Oil and Gas Reporter is a forum for presenting mini-case studies.

PTD. PTTC and World Oil have worked with producers and technology providers to present case studies since 1999 (www.pttc.org/case_studies/case studies.htm). Several have dealt with hydraulic fracturing aspects. Details from three are shared below, but information from all case studies is online.

Fracture mapping and modeling optimize CBM treatments (June 2004, www.pttc.org/case_studies/PTdigest06-04.htm). Anadarko Petroleum employed advanced fracture mapping technology by using new, in-well tiltmeters and fracture modeling to optimize hydraulic fracture stimulation in two coalbed methane (CBM) plays.

The plays are in Utah’s Helper field and the Copper Ridge field of southwestern Wyoming. At Helper, tiltmeter data proved that single-stage treatments could stimulate the entire multi-seam interval. Savings of $35,000 to $50,000/well were realized, compared to prior multiple-stage treatments. At Copper Ridge, treatments were optimized to stay away from permeable water sands. Savings from reduced water production were $1.3 million in the first year. In addition, individual well treatment costs range from $100,000 to $150,000 less per well.

An impressive frac job was carried out by BJ Services for Anadarko Petroleum on an 18,000-ft completion in North Texas. The four-stage completion required 19 frac pumps, each delivering 2,700 hydraulic hp at up to 15,000 psi. About 450,000 lb of bauxite were placed in the formation. Photo courtesy of BJ Services.

Frac modifications identified through virtual intelligence increase production (Dec. 2002, www.pttc.org/case_studies/case_studies_archived/PTdigest12-02.htm). Occidental used Artificial Neural Network Modeling to identify changes that would improve hydraulic fracturing effectiveness in its Western Shallow Oil Zone completions at Elk Hills, California. Modeling showed practices that would improve output, including changes in pay selection and perforating practices, stimulation fluid type and volume, and breaker selection. Modeling showed that altered completion/ frac procedures could double output. Implementing these changes increased average completion values by $170,000.

Solutions from the field, summaries of PTTC workshops. Through the years, experts from producers, the service sector and R&D specialists have presented insights in PTTC workshops, now totaling about 150 events annually. PTTC captures insights from many of them. For hydraulic fracturing, a prime example is the 2004 workshop developed by Dr. Jennifer Miskimmons, Colorado School of Mines. Her material, summarized online (www.pttc.org/solutions/sol_2004/533.htm), addresses such questions as: What goes into designing a frac treatment? What can’t modeling tell you? How do you analyze your treatment’s success?

Miskimmons leads the FAST (fracturing, acidizing, stimulation technology) Consortium at Colorado School of Mines (www.mines.edu/fast/new_page_1.htm). FAST concentrates on theoretical and laboratory developments that can be used in the field to improve stimulation design and execution. Some PTTC workshops focus on individual plays, as did a 2000 session (www.pttc.org/solutions/208.htm) in Kansas that provided insights on hydraulic fracturing practices.

Network News, PTTC’s quarterly newsletter. PTTC has had, in its newsletter, “state-of-the-art” summaries that present insights on selected topics. An issue in 2001 (www.pttc.org/news/v7n1nn5.htm) focused on “Improvements in hydraulic fracturing.” Topics included diagnostics, microseismic fracture mapping, downhole tiltmeter fracture mapping, waterfracs, damage removal, and restimulation candidate selection.

Contributions to trade journals. PTTC also develops technical articles for trade journals. A good example is “Advances improve hydraulic fracturing” in American Oil and Gas Reporter’s Dec. 2001 issue. This and other Tech Connections columns can be viewed online at www.pttc.org.

Society of Petroleum Engineers. SPE is the logical professional group with the most published technical info, but all engineers should still have several good, long conversations with geological colleagues. It will pay dividends in understanding individual reservoir rocks. SPE has three main gold mines – e-library papers, insights from Applied Technology Workshops and Distinguished Lecturer presentations. The e-library is great for focused topics, like the Barnett Shale website that PTTC’s Texas Region built (http://www.energyconnect.com/pttc/BSR/). There, within the Publications section, is a list of SPE papers focused on different Barnett Shale aspects, many focusing on hydraulic fracturing.

Applied technology workshops (ATWs). Insights and/or full presentations from these topical workshops are often posted on SPE’s website (www.spe.org), to Technical Resources, then Technical Summaries, and then ATW Summaries. The following discussion shows information that can be found by using a 2003 ATW on “Novel advances in tight gas completion.” Developed by SPE members in the Gulf Coast, Mexico and Southwest Texas regions, this ATW focused on hydraulic fracturing. Synopses on two topics below are examples.

Refrac technologies (John Ely, Ely and Associates, www.spe.org/specma/binary/files/156857203acor_session6_1ely.pdf). In this overview of why restimulations are needed, most wells suffer from proppant pack impairment. Thus, candidate selection is key. Additional topics include: load recovery has no relation to well productivity; logistics of refracing large intervals (stacked pays); and waterfrac applications – interbedded, stacked, low-permeability pays (Mesa Verde, Barnett Shale, Bossier Sand). Quoting the final slide, “The absolute key to success relates to candidate selection. The selection process begins with taking advantage of local knowledge, then moves to simplified moving domain analysis. Subsequently, more complicated tools can be brought to bear.”

Calibrating fracture models with diagnostic fracture measurements, (Mike Meyerhoffer, Pinnacle Technologies, www.spe.org/specma/binary/files/156857603acor_session6_3meyerhoffer.pdf). Efforts to reconcile predictive models with direct observations of fracture growth are detailed. Pressure matching inferred geometry does not always fit directly measured geometry. So, this process goes one step beyond net pressure history matching by calibrating fracture growth model behavior with measured growth behavior. These enhanced data allow model recalibration.

Two case histories are reviewed – Cotton Valley, East Texas, and Treatment Well Tiltmeter, Coalbed Methane, Wyoming. In the latter case, a tiltmeter is lowered into a well that is being stimulated, to get real-time data. However, this method does not yield a length estimate. Model calibration parameters include tip effects, pressure profile along fracture length, composite layering effect (mechanical rock properties) and multiple fractures.

Distinguished Lecturer presentations. In this SPE program, industry personnel share insights from individual and industry perspectives. An example is the 2001 – 2002 case study presentation (Hydraulic Fracturing Restimulation) by Steve Wolhart of Pinnacle Technologies (http://www.spe.org/specma/binary/files/10403300102dl_wolhart.pdf). Wolhart highlights results from the then-Gas Research Institute’s “Restimulation Project” that analyzed data in four basins – Green River (Frontier formation), Piceance (Williams Fork), East Texas (Cotton Valley), and Fort Worth (Barnett Shale). Quoting from their conclusions, “Case histories show restimulation potential despite negative industry perception.” A single selection technique (to identify candidate wells) remains elusive. Virtual intelligence and type curves offer the best results, but one must consider the reservoir when selecting the method.

Energy Dept. R&D results/ reports. Findings from most publicly supported R&D projects are online. DOE’s federal tax dollars support specialized studies, such as “Selection and treatment of stripper gas wells for production enhancement in the Mid-continent” (www.netl.doe.gov/scngo). There’s also an item about gas storage applications on PTTC’s Appalachian Region website (http://karl.nrcce.wvu.edu/regional/fracstim.pdf).

Trade journal listings. Technology insights can be found in the trade journals. For US E&P, those of most direct interest are World Oil, American Oil and Gas Reporter and Hart’s E & P. It is easiest to find information at World Oil (www.worldoil.com/magazine/magazine_contents.asp), since they put more articles online and have a convenient search feature. Searching on hydraulic fracturing found several articles (excluding PTD case studies). Among the more interesting are “Low-density propping agents improve hydraulic fracturing” (June 2004), “Improved fracturing avoids proppant flowback” (July 2004), and “France: Hydraulic fracture monitoring aids in optimizing recovery” (April 2005).

A search feature was not evident for Hart’s E & P (www.eandpnet.com). Often, the American Oil and Gas Reporter publishes extended case studies, such as the May issue’s “Optimizing completions boosts performance of tight gas wells,” p. 60 – 67. However, one needs a hardcopy subscription, because articles are not placed online. 

THE AUTHOR
	E. Lance Cole is a registered professional engineer in Oklahoma and has served as PTTC’s National Project Manager since 1996. Responsibilities include technical oversight of PTTC’s regional programs, reporting, communications and outreach. Mr. Cole’s experience includes reservoir and corrosion engineering, plus reserve estimation and appraisal. He has worked with a major oil company, a large integrated independent, and in engineering-oriented consulting companies. He holds a BS degree in chemical engineering from South Dakota School of Mines and an MS degree in management from Southern Nazarene University.