Elk Hills Research Articles

Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage

Hydrocarbons from the Elk Hills Naval Petroleum Reserve (NPR#1), Bakersfield, CA, are enriched in heavy noble gases. The 132Xe/ 36Ar ratios are as high as ∼576 times the ratio in air and represent the largest relative Xe-enrichments ever observed in terrestrial fluids. The Xe isotopic composition is indistinguishable from air. We show that these samples cannot be explained by equilibration of oil with air saturated water and secondary enrichment via a Rayleigh distillation gas stripping process. Based on laboratory studies of others with potential petroleum source rocks, we believe the source of this enriched heavy noble gas component was adsorbed air initially trapped in/on the source rocks that was expelled and mixed with the hydrocarbons during expulsion and primary migration. Kr and Xe enrichments decrease with increasing 36Ar concentration. We propose a model in which an initial Kr–Xe-enriched hydrocarbon becomes diluted with noble gases extracted from air saturated groundwater during expulsion, migration, and storage. The model generates an integrated water/hydrocarbon ratio for the production fluid which indicates a minimal role for water in hydrocarbon expulsion and migration. The results are interpreted to provide time/geometrical constraints on the mechanisms by which hydrocarbons can migrate as a separate phase.

Abstract: Preservation of Porosity in Quartz-Phase Porcelanite Reservoirs, Monterey Formation, Elk Hills Field, California 

Abstract: Preservation of Porosity in Quartz-Phase Porcelanite Reservoirs, Monterey Formation, Elk Hills Field, California 

Tempest over Teapot Dome: the story of Albert B. Fall

Albert B. Fall, interior secretary in the Harding administration, was the first American cabinet member sent to prison for a crime committed in office. In the Teapot Dome affair - the worst modern political scandal until Watergate - Fall leased two naval oil reserves, Wyoming's Teapot Dome and California's Elk Hills, to Harry F. Sinclair and Edward L. Doheny and received payments of $404,000 from the two millionaire oilmen. Historian David Stratton pulls no punches as he sheds new light on western and national politics, conservation, and economic development in the late nineteenth and early twentieth centuries.Tempest over Teapot Dome describes Fall's role in Harding's administration, his tribulations in court before going to prison in 1931, his freewheeling career in New Mexico politics, his lawyering for underdog ranchers in a bloody range war, his gut-fighting style as a U. S. senator who opposed Woodrow Wilson's foreign policy, and his strident activities as an expert on Latin American affairs, particularly U. S.-Mexican relations. Fall's belief in the unrestricted and immediate disposition of public lands was as typically western as his black, broad-brimmed Stetson hat and his love of fine horses.

The thermal and cementation histories of a sandstone petroleum reservoir, Elk Hills, California: Part 2: in situ oxygen and carbon isotopic results

Liquid hydrocarbon accumulations within the Elk Hills and North Coles Levee oil fields, southern San Joaquin basin, are largely isolated within calcite-cemented reservoirs comprised of late Miocene Stevens sandstone. We undertook ion microprobe carbon and oxygen isotope ratio measurements on calcite cements to assess both the source of the carbon and the temperature of cementation. By combining thermal history results from 40 Ar/ 39 Ar analyses (reported in the companion study) with calculated cementation temperatures based on our oxygen isotope measurements, a model cementation history is derived which indicates that carbonate precipitation occurred primarily between 4 and 6.5 Ma. Conventional oxygen isotopic measurements yield a more restricted range of isotopic compositions reflecting the averaging properties of that method. The associated carbon isotopic measurements suggest that most of the early cements were derived from a marine carbonate source or a mixture of marine carbonate and lighter carbon from maturing hydrocarbons. Carbonates precipitated most recently (and thus at the highest temperatures) contain light carbon, interpreted to result from thermal decomposition of kerogen in the interbedded shales. Based on the light carbon values (<−10‰ PDB) and low range of temperatures over which the bulk of the cement formed, the maturation of petroleum in the interbedded shales likely postdates cementation.

The thermal and cementation histories of a sandstone petroleum reservoir, Elk Hills, California: Part 1: [formula omitted] thermal history results

Recent developments in K-feldspar 40 Ar/ 39 Ar thermochronometry have provided new tools to deal with interpretive impediments that previously limited its application to investigating sedimentary basin thermal histories. These new methodologies were applied to detrital K-feldspars recovered at various depths from a deep well drilled through a carbonate-cemented sandstone petroleum reservoir in the southern San Joaquin Valley, California. Thermal histories obtained from both thermochronological analysis and burial history constraints were used to constrain a conductive heat flow model of basin evolution. The basin appears to have experienced a broadly linear heating history due to burial throughout the early and middle Miocene followed by a significant increase in heating rate between 9 and 6 Ma. In a companion paper [Mahon, K.I., Harrison, T.M., McKeegan, K.D., 1998. The thermal and cementation histories of a sandstone petroleum reservoir, Elk Hills, California. Part 2: In situ oxygen and carbon isotopic results. Chem. Geol. 152, 257–271], we apply the thermal model to predict the temperature evolution of the much shallower late Miocene Stevens sands, a prolific petroleum producer. Ratios of excess 40 Ar to chlorine calculated from the differential release of radiogenic and nucleogenic argon during isothermal heating steps indicate a uniform value of 5.4±0.9×10 −5 over the 2.5 km vertical distance separating the samples from well 934-29R suggesting that the basin receives a high basal flux of radiogenic argon.

Abstract: Preliminary Quantification of Adsorbed Gas in Monterey Shale Reservoirs at Elk Hills, Kern County, California&amp;nbsp;

Abstract: Preliminary Quantification of Adsorbed Gas in Monterey Shale Reservoirs at Elk Hills, Kern County, California&amp;nbsp;

Abstract: Case Study of a Successful Low-Cost, Low-Pressure, Low-Volume Gas Injection Project in the Shallow Oil Zone, Naval Petroleum Reserve #1 (Elk Hills), Kern County, CA&amp;nbsp;

Abstract: Case Study of a Successful Low-Cost, Low-Pressure, Low-Volume Gas Injection Project in the Shallow Oil Zone, Naval Petroleum Reserve #1 (Elk Hills), Kern County, CA&amp;nbsp;

Abstract: The Use of Horizontal Drilling to Improve Production from a Tight P1iocene Reservoir, Westem Shallow Oil Zone: Elk Hills, U. S. Naval Petroleum Reserve #1, Kern County, California&amp;nbsp;

Abstract: The Use of Horizontal Drilling to Improve Production from a Tight P1iocene Reservoir, Westem Shallow Oil Zone: Elk Hills, U. S. Naval Petroleum Reserve #1, Kern County, California&amp;nbsp;

Abstracts: A Gravity Model of The Southern San Joaquin Basin Constrained by Density Data from a 24,000 Foot Well, Elk Hills, California&nbsp;&nbsp;

Abstracts: A Gravity Model of The Southern San Joaquin Basin Constrained by Density Data from a 24,000 Foot Well, Elk Hills, California&nbsp;&nbsp;

Abstract: Making Better Structure Maps by Combining Direct Mapping and Conformable Mapping Techniques: An Example from the United States Naval Petroleum Reserve No. 1, Elk Hills, CA&nbsp;

Abstract: Making Better Structure Maps by Combining Direct Mapping and Conformable Mapping Techniques: An Example from the United States Naval Petroleum Reserve No. 1, Elk Hills, CA&nbsp;

Abstract: Chemical and Isotopic Studies of Oil Field Waters and Gases: Elk Hills Region, CA&amp;nbsp;

Abstract: Chemical and Isotopic Studies of Oil Field Waters and Gases: Elk Hills Region, CA&amp;nbsp;

Abstract: Geology &amp;amp; Production Implications of Debris Flows in the C &amp;amp; D Shale Reservoirs, Elk Hills Giant Oil Field, California&amp;nbsp;

Abstract: Geology &amp;amp; Production Implications of Debris Flows in the C &amp;amp; D Shale Reservoirs, Elk Hills Giant Oil Field, California&amp;nbsp;

Abstract: Development of a Geostatistical Model for Reservoir Simulation of a Peripheral Waterflood in the Main Body B Turbidite Reservoir, Elk Hills Field, California&amp;nbsp;

Abstract: Development of a Geostatistical Model for Reservoir Simulation of a Peripheral Waterflood in the Main Body B Turbidite Reservoir, Elk Hills Field, California&amp;nbsp;

Abstract: Application of Geostatistical Modeling and Reservoir Simulation in Management of a Turbidite Reservoir Waterflood, Elk Hills Oil Field, California&amp;nbsp;

Abstract: Application of Geostatistical Modeling and Reservoir Simulation in Management of a Turbidite Reservoir Waterflood, Elk Hills Oil Field, California&amp;nbsp;

Improved oil recovery using horizontal wells at Elk Hills, Californi : F. J. Gangle, K. L. Schultz, G. S. McJannet & N. Ezekwe, SPE Drilling & Completion, 10(1), 1995, pp 27–33

Improved oil recovery using horizontal wells at Elk Hills, Californi : F. J. Gangle, K. L. Schultz, G. S. McJannet & N. Ezekwe, SPE Drilling & Completion, 10(1), 1995, pp 27–33

Application of Turbidite Facies of the Stevens Oil Zone for Reservoir Management, Elk Hills Field, California: ABSTRACT

A detailed depositional model for the uppermost sand reservoirs of the Stevens Oil Zone, Elk Hills Field, California, contains three facies: turbidite channel-fill sand bodies, overbank Sandstone and mudstone, and pelagic and hemipelagic siliceous shale. Sand bodies are the primary producing facies and consist of layered, graded sandstone with good permeability. The presence of incipient anticlines with subsea relief in the late Miocene resulted in deposition of lenticular and sinuous sand Was within structurally created channels. Relief of these structural channels was low when the earliest sand bodies were deposited, leading to a wide channel complex bounded by broad overbank deposits of moderate to low permeability. As deposition proceeded, increased structural relief constrained the channels, resulting in narrower sand body width and relatively abrupt channel terminations against very low permeability siliceous shale. With post-Miocene uplift and differential compaction, stratigraphic mounding of sand bodies helped create structural domes such as the 24Z reservoir. Stratigraphic traps including the 26R reservoir were also created. Such traps vary in seal quality from very effective to leaky, depending on the lateral transition from sand bodies to siliceous shale. Application of the Elk Hills turbidity model (1) provides a framework for monitoring production performance in themore » 24Z and Northwest Stevens waterflood projects; and for tracking gas migration into and out of the 26R reservoir, (2) helps b identify undeveloped locations in the 26R reservoir ideally suited for horizontal wells, (3) has led to the identification of two new production trends in the 29R area, and (4) makes possible the development of exploration plays in western Elk Hills.« less

Characteristics of the C Shale and D Shale Reservoirs, Monterey Formation, Elk Hills Field, Kern County, California: ABSTRACT

The upper Miocene C Shale and D Shale reservoirs of the Elk Hills Shale Member of the Monterey Formation have cumulative oil and gas production much higher than the originally estimated recovery. These San Joaquin basin reservoirs are the lowest of the Stevens producing zones at Elk Hills and currently produce from a 2800-acre area on the 31 S anticline. The C Shale contains lower slope and basin plain deposits of very fine grained, thinly bedded, graded turbidites, pelagic and hemipelagic claystone, and slump deposits. Although all units are oil-bearing, only the lower parts of the graded turbidity intervals have sufficient horizontal permeability to produce oil. The D Shale consists of chart, claystone, carbonates and slump deposits, also originating in a lower slope to basin plain setting. All D Shale rock types contain oil, but the upper chart interval is the most productive. The chart has high matrix porosity, and due to a complex horizontal and vertical microfracture system, produces at a highly effective rate. Core samples indicate more oil-in-place is present in the thin, graded C Shale beds and in the porous D Shale chart than is identifiable from conventional electric logs. High gas recovery rates are attributed mostlymore » to this larger volume of associated oil. Gas also enters the reservoirs from the adjacent 26R reservoir through a leaky normal fault. Significant gas volumes also may desorb from immature organic material common in the rock matrix.« less

Reservoir Compartmentalization Caused by Mass Transport Deposition, Northwest Stevens Pool, Elk Hills Naval Petroleum Reserves, California: ABSTRACT

The [open quotes]A[close quotes] sands of the Northwest Stevens Pool consist of six major subdivisions (A1-A6) and numerous sublayers. These sands are above the [open quotes]N Point[close quotes] stratigraphic marker, making them much younger than most other Stevens sands at Elk Hills. Cores show the A1-A3 sands to be possibly mass transport deposition, primarily debris flows, slumps, and sand injection bodies. The A4-A6 sands are characterized by normally graded sheet-like sand bodies Hospital of traditional outer fan turbidite lithofacies. Most current production from the A1-A2 interval comes from well 373A-7R, are completed waterflood wells that came on line in 1992 at 1400 BOPD. Well 373A-7R is an anomaly in the A1-A2 zone, where average production from the other ten wells is 200 BOPD. Other evidence for compartmentalization in the A1-A2 interval includes sporadic oil-water contacts and drawdown pressures, difficult log correlations, and rapid thickness changes. In 1973, well 362-7R penetrated 220 ft of wet Al sand. The well was redrilled updip and successfully completed in the A1, where the oil-water contact is more than 130 ft lower than the original hole and faulting is not apparent. In 1992, horizontal well 323H-7R unexpectedly encountered an entirely wet Al wedge zone. Reevaluation more » of the A1-A3 and other sands as mass transport origin is important for modeling initialization and production/development strategies. « less

Coupling Geostatistics to Detailed Reservoir Description Allows Better Visualization and More Accurate Characterization/Simulation of Turbidite Reservoirs: Elk Hills Oil Field, California: ABSTRACT

Coupling Geostatistics to Detailed Reservoir Description Allows Better Visualization and More Accurate Characterization/Simulation of Turbidite Reservoirs: Elk Hills Oil Field, California: ABSTRACT

Improved Oil Recovery Using Horizontal Wells at Elk Hills, California

Abstract Eight horizontal wells have been drilled and completed in a steeply dipping Stevens sand reservoir in the Elk Hills field, Kern County, California. The subject reservoir, called the Stevens 26R, is a turbidite channel sand deposit one mile wide, three miles long, and one mile deep. Formation beds have a gross thickness up to 1,500 feet and dips as high as 60 degrees on the flanks. The original oil column of 1,810 feet has been pulled down to 200 feet by continual production since 1976. The reservoir management operating strategy has been full pressure maintenance by crestal gas injection since 1976. The steep dip of the formation makes gravity drainage the dominant drive mechanism. Additionally, improved recovery is coming from cycling dry gas through the large secondary gas cap region. The prudent placement of the horizontal wells above the oil/water contact promises to improve oil recovery and extend the operating life of the reservoir. Field results are given to compare the performance of the horizontal wells with the conventional wells. The horizontal wells produce at higher rates, lower draw downs, and lower gas/oil ratio which will extend the life of the project and result in higher recovery.