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.

Reservoir Rocks of Persian Oil Fields

Abstract: The paper gives a description of the reservoir rocks of three fields, Masjid-i-Sulaiman, Haft Kel, and Naft Khaneh. The reservoir rock is a limestone of Lower Miocene age called the Asmari limestone. It is a fine-grained foraminiferal limestone, mostly of low porosity, and the porosity of the rock is independent of the degree of dolomitization. Fracturing of the rock is the most important factor governing production.

Diagenetic Heterogeneity and Reservoir Quality: Fluvial, Deltaic, and Turbiditic Sandstone Reservoirs, Potiguar and Recôncavo Rift Basins, Brazil

Abstract: Fluvial and lacustrine (deltaic and turbiditic) sandstones are major hydrocarbon reservoirs in the onshore (Lower Cretaceous) Potiguar and Reconcavo rift basins in northeastern Brazil. Diagenetic elements including mechanically infiltrated (MI) clay, calcite, dolomite, and chlorite show distinct distribution patterns at interwell and field-wide reservoir scales. Such distributions, and thereby diagenetic heterogeneity, have been modeled based on thin-section, core, well-log, and petrophysical data. At the interwell scale, relationships between sandstone body geometry and the distribution of diagenetic elements are a critical aspect of reservoir heterogeneity. At this level, (1) MI clay concentrations occur in fluvial reservoirs following the orientation of paleochannels, generating strong compartmentalization of the reservoirs, (2) calcite cement appears either concentrated near sand-shale contacts (peripheral distribution) or dispersed in the interior of the sandstone layers (scattered distribution), (3) dolomite cement may appear concentrated along laminations in cross-stratified sandstones, causing a decrease of one order of magnitude in the effective horizontal permeability, and (4) authigenic chlorite is observed to reduce more significantly the permeability in fine-grained sandstones than in coarse-grained sandstones, an effect that may cause important modifications in the permeability structure of the reservoirs. At the field-wide scale, diagenetic heterogeneity includes (1) stratigraphic zonation of diagenetic properties in fluvial reservoirs, (2) increasing carbonate cementation toward the border of the hydrocarbon accumulations in deltaic reservoirs, and (3) distinct patterns of carbonate cementation observed in channel fills and lobes in turbiditic reservoirs. Incorporating the distribution and effects of diagenetic elements into the interwell and field-wide geological modeling is essential to achieve a realistic reservoir representation. Such incorporation is performed by the integration of diagenetic properties with other geological attributes, including nature and distribution of depositional facies, structural elements, and stratigraphic framework. This procedure improves reservoir quality evaluation and leads to more precise prediction of reservoir performance.

Characterization of diagenetically altered carbonate reservoirs, South Cowden Grayburg Reservoir, West Texas

Abstract: Much of the difficulty in constructing carbonate reservoir models for fluid-flow simulation results from diagenetic overprinting of depositional permeability patterns. In the South Cowden field, diagenetic effects result in (1) low porosity and permeability in the western and northern areas due to reduction of porosity by means of dolomitization and post-dolomitization compaction, (2) elimination of the petrophysical effects of depositional texture resulting from changes in particle size due to dolomitization, and (3) creation of a touching-vug pore system due to anhydrite dissolution. The extent of anhydrite alteration can be mapped to show three distinct diagenetic areas: those dominated by unaltered, altered, or dissolved anhydrite. Each alteration type has a unique acoustic-porosity transform that can be used to map the diagenetic areas and to calculate porosity when only acoustic logs are available. A single porosity-permeability transform characterizes the areas having unaltered and altered anhydrite, and the depositional stratigraphy is useful in constructing a reservoir model. A more favorable transform characterizes the area of dissolved anhydrite, and depositional stratigraphy is not useful in constructing a reservoir model because of the large effect of the diagenetic overprint.

Geophysical Well Log Study on the Paleoenvironment of the Hydrocarbon Producing Zones in the Erchungchi Formation, Hsinyin, SW Taiwan

Abstract: Gamma ray log facies of nine wells were used to reflect the vertical profile of grain size and were combined with well sample data to deduce the paleoenvironment of the Erchungchi ”A” Member in the Hsinyin and Pachanchi areas. Four log facies were recognized in the studied intervals: a thick funnel-shaped facies representing a prograding delta; a thin funnel-shaped facies representing a crevasse splay; a boxcar-shaped fades representing a distributary channel; a bell-shaped facies representing a fluvial or deltaic channel. The paleoenvironment of the Erchungchi ”A” Member in the Hsinyin area is mainly an imbricated delta system whose thickest lobe is located in Well S-1. The delta was first deposited in the headstreams of the submarine channels, followed by mudstones as cap rocks which seal hydrocarbons in stratigraphic traps. There are many submarine channels in southwestern Taiwan, so similar stratigraphic hydrocarbon trap conditions may occur elsewhere in southwestern Taiwan.