Table of Contents

Vol. 7, No. 1
1st Quarter 2001

Horizontal Drilling for Improved Recovery

June 11, 1999 (Hobbs, NM) by Southwest Region

BOTTOM LINE

In the proper reservoir application, horizontal wells yield higher production rates and recovery than vertical wells, yielding attractive economics even though cost may be twice that of vertical wells. Numerous technology advances continue to improve horizontal well performance and broaden application. Among those, underbalanced drilling with its many benefits has probably had the most profound effect.

PROBLEM ADDRESSED

Long reserve life indexes are no longer accepted. Operators are looking for technologies that will enable them to produce more of discovered reserves and produce them faster. Horizontal wells can be an attractive option for doing that because of their greater reservoir exposure, particularly where reservoir heterogeneities are pronounced. Horizontal well development can occur through new wells or re-entry operations, and can be single or multilateral applications.

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Managing California's Oil Resources

December 6, 2000 (Los Angeles, CA) by West Coast Region

BOTTOM LINE

Continued technology advancements and application are essential for continued profitability in mature US reservoirs. Current Department of Energy (DOE) stripper well projects provide some options for independents to participate in applied R&D. To maintain profitability in mature reservoirs, independents must optimally apply newer technologies such as horizontal well technology and 3-D visualization. Often, it is a buffet of technologies that must be applied. Three major California independents—Oxy USA in Thums Long Beach Unit, Nuevo Energy Company, and Berry Petroleum Company—shared their experiences in revitalizing leases through applying a mix of technologies.

PROBLEM ADDRESSED

With independents responsible for increasing percentages of drilling and oil and gas production, independents must take advantage of available applied R&D opportunities, and their role in encouraging human resource development must increase if academia is to deliver future geoscientists. To overcome hesitance that they can profitably apply newer technologies, independents rely heavily on other's experiences or case studies to develop the confidence they need to implement technologies.

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Distributed Energy Resources in the Oil Patch

May 15, 2000 (Houston, TX) by Central Gulf and Texas Regions

BOTTOM LINE

By placing power-generating units capable of running off of field gas onsite, an operator can lower lifting costs substantially. In addition, locating Distributed Energy Resources (DER) in areas where excess power can be sold into the grid could produce a substantial new revenue stream.

PROBLEM ADDRESSED

Advanced technologies with great promise for reservoir characterization studies are being developed at the Bureau of Economic Geology, The University of Texas at Austin. Advanced visualization, especially virtual imaging, has already begun to redefine approaches to characterization and field management. A new multi-component seismic technique, currently being developed, will provide better understanding of stratigraphic relationships, lithological distributions, and pore-fluid properties. Quartz-filled microfractures in clastic sediments from fractured reservoirs are being utilized to quantify the size distributions of much less abundant macrofractures that can control fluid flow. This technique is proving to be a cost-effective way to construct a dual-porosity simulation for large regions in the subsurface. Borehole imaging logs, when properly calibrated with core, can resolve facies successions and some karst features with degrees of accuracy that can rival core description.

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Seals—A Cirtical Element to Successful Exploration and Production

March 29, 2000 (Jackson, MS.) by Eastern Gulf Regions

BOTTOM LINE

eals are commonly an overlooked component in the evaluation of a potential hydrocarbon accumulation. Seals can be detected by a variety of tools such as pressure tests, seismic amplitude analysis, and high pressure capillary curves. Capillary pressure tests are a very useful method to evaluate seals.

PROBLEM ADDRESSED

In order for a hydrocarbon accumulation to exist there must be reservoir rocks, seals, a trap, and hydrocarbon charge. Because seal capacity is the maximum hydrocarbon column height that a seal can trap, seals can be defined by high pressure mercury-air capillary curves. Capillary pressure in rocks is controlled by interfacial tension, wettability, and the pore throat size distribution. Capillary pressure tests are extremely useful in determining the accumulation process and the initial distribution of reservoir fluids. They are also very useful for consideration of waterflood and water drive behavior.

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Optimization of Infill Drilling in Naturally Fractured Tight Gas Sandstone Reservoirs in the San Juan Basin

May 11, 2000 (Farmington, NM) by Southwest Region

BOTTOM LINE

Integrated, multi-disciplinary reservoir characterization and simulation studies of tight gas sandstone reservoirs in the San Juan Basin are required to determine the optimum location and expected recovery from infill wells. Core and outcrop analysis, seismic data, production data analysis techniques and reservoir simulation are tools used in the analysis. A spreadsheet-based infill drilling locator program has been developed to assist producers in analyzing infill drilling potential in these and other similarly fractured reservoirs. 

PROBLEM ADDRESSED

Production from tight gas sandstone reservoirs in the San Juan Basin is highly dependent on natural fractures. Although enhancing overall permeability, the fractures create significant permeability anisotropy, which causes drainage areas around wells to be elliptical. Elongated drainage areas increase the potential for large sections of the reservoir being undrained. To optimally site infill wells, and know that there are sufficient reserves to justify drilling, one must understand reservoir geology, the natural fracture system, drainage patterns and the relative stage of depletion. Further data analysis and numerical modeling are often warranted to define upside potential.