Petroleum reservoir

About: Petroleum reservoir is a research topic. Over the lifetime, 5403 publications have been published within this topic receiving 83535 citations. The topic is also known as: petroleum deposit.

Hydrocarbon Exploration in Western Oregon and Washington

Abstract: Continuing development of the Mist gas field and stepout discovery wells affirm the hydrocarbon prospectivity of western Oregon and Washington. Understanding the factors controlling the Mist gas field accumulation helps define an exploration strategy for the Pacific Northwest. Reservoir sandstones in the Mist area are in the Cowlitz Formation of middle to late Eocene age. Reservoir-quality sandstones have average porosities of 25% and average permeabilities of 200 md. The reservoir sands are well-sorted feldspathic-quartzose sandstones and are less susceptible to diagenetically formed pore-filling authigenic minerals than are the more lithic sandstones of other horizons and less well-sorted depositional environments. Potential hydrocarbon source rocks consist of marine shale to coaly facies. Organic matter is predominately terrestrially derived. Mist gas field pools are small and have variable gas types, suggesting to some workers that the gas is generated from rocks immediately adjacent to the reservoir. Gas wetness and ^dgr13C values indicate that gas from the Bruer, Flora, and Newton pools is probably thermally generated. Shales encasing the Mist gas field sandstone reservoirs are thermally immature, having vitrinite reflectance values less than 0.4%. Thermal gas most likely would have been generated downdip within nearby depocenters and migrated into the reservoir. The integration of paleogeographic models for mineralogic provenance, well-sorted sand accumulation, and thermal maturation within Cenozoic depocenters provides an exploration strategy for defining areas of highest hydrocarbon potential in western Oregon and Washington. Each of the many Eocene formations in Oregon and Washington with relatively lithic-free, feldspathic-quartzose mineralogy should be evaluated as a potential target.

Numerical Simulation of Oil Production With Simultaneous Ground Subsidence

Abstract: A 2-phase, 2-dimensional black oil simulator was developed for simulating reservoir production behavior with simultaneously occurring reservoir formation compaction and ground subsidence at the surface. The simulator was designed in particular for application to the Bolivar Coast fields of W. Venezuela, where extensive ground subsidence has been in evidence for many years. The flow equations were solved by both ADIP and SIP (Strongly Implicit Procedures). Reservoir compaction was described on the basis of the experimental data reported to date. The magnitude of areal subsidence at the surface was calculated using reservoir compaction, utilizing the recently developed theory of poro-elasticity. The model was employed for generating the reservoir formation profiles, as well as the ground subsidence bowls for a variety of conditions. It was found that the subsidence behavior strongly depends on the depth of burial. For example, with an increase in the depth, the reservoir bottom surface may actually uplift, while the top surface subsides. (21 refs.)

Monterey Formation porcelanite reservoirs of the Elk Hills field, Kern County, California

Abstract: Oil and gas production from Monterey Formation porcelanite at the Elk Hills field in California's San Joaquin basin occurs from intervals that have quartz-phase mineralogy. However, characteristics differ from chert and porcelanite reservoirs of the coastal California Monterey Formation in that matrix porosity is more typical of the opal-CT phase, petroleum storage is mostly in the matrix, and natural fracture patterns are dominantly small scale. Several Elk Hills reservoirs located on two large anticlines produce from porcelanite. The 29R AB and 31S D are the most productive porcelanite reservoirs, each having cumulative oil production of about 40 million bbl. Although interbedded with siliceous shale, sandstone, and dolomite, most of the porous reservoir rock is laminated porcelanite. Porosity averages between 20 and 25% and is evenly distributed throughout the porcelanite as extremely small pores ranging in size from 1 to 10 µm. Matrix permeability averages 0.8 md, but flow of oil and gas is enhanced through fractures parallel with and perpendicular to bedding. Higher than anticipated porosity may be in part due to migration of hydrocarbons into the porcelanite reservoirs while still in opal-CT-phase mineralogy. The dissolution of opal-CT and precipitation of quartz occurs in place, and the resulting quartz-phase mineral structure mimicks the porous opal-CT framework.

Stratigraphic Traps in a Valley Fill, Western Nebraska

Abstract: Oil is trapped in a trend of valley-fill sandstone bodies in the Cretaceous "J" interval in Cheyenne and Morrill Counties, Nebraska. The valley fill is composed chiefly of porous and permeable sandstone; it trends north-south and is about 1,500 ft. wide and 50 ft. thick. Oil has accumulated in the valley fill where it crosses the axes of northwest-plunging anticlines. Updip (eastward) escape of oil is prevented by the enclosing marine sediments of the "J" interval, in which sandstone beds with low oil-entry pressures are discontinuous and separated by sandstone or shale beds with higher oil-entry pressures. The traps therefore involve a combination of stratigraphic and structural conditions. The "J" in this area is a sandstone and siltstone unit, 38-77 ft. thick, deposited in predominantly marine environments. The "J" is overlain and underlain by dark gray marine shale. The interval can be divided into two marine members, an upper and a lower, each relatively thin and with distinctive mineralogy, sedimentary structures, fossil content, and electric-log character. These members can be traced over hundreds of square miles in western Nebraska. After deposition of the upper member, the area emerged and a stream cut a narrow valley which was filled mainly with sandstone of distinctive character. The stream in the valley cut through most or all of the two previously deposited marine members. The trend of the valley fill is nearly straight, suggesting that erosion and deposition were the work of a meandering stream whose width was much less than that of the valley. Seven fields have been discovered along the valley-fill trend within the study area. One well of every 1.9 wells drilled into the valley fill has been completed successfully. These wells are rated as good producers and have long productive lives by Denver basin standards. Some production also has been developed in marine sandstone beds of the "J" near the area of the valley fill, but only one well of approximately every 10.9 drilled is completed successfully; moreover, productivity commonly is low and total reserves are small. Therefore, stratigraphic study leading to an improved understanding of the genesis and form of the sandstone reservoirs is of considerable economic value.