Types Of Xujiahe Formation In Central Sichuan Gas Reservoir And Enrichment Regularity

The gas distribution is very broad in Xujiahe Formation in the centre of Sichuanarea. The section-two, section-four, section-six are the main gas-producing zone onthe longitudinal.Litho logic gas reservoir is the main kind. The distribution thecharacteristics of conation gas in a larger area and enrichment of advantage. Researchdrilling coring analysis data, down hole test data, reservoir properties based oninformation utilization sediment logy, sequence stratigraphy, petroleum geology, organicgeochemistry multidisciplinary theories and research methods, to xujiahe Formation inthe centre of sichuan area structure, sedimentary, reservoir, source rock characteristicswere analyzed by gas reservoir types of induction, gas reservoir description of thecharacteristics and anatomy of a typical gas reservoirs, gas reservoirs in central Sichuansummarize the distribution and accumulation. Recognizing the results obtained are asfollows:1The xujiahe reservoir to be two、four、six shall be mainly from the physicaldistribution, Xujiahe sandstone generally has low porosity and low permeability~special low porosity and permeability characteristics, but longitudinally good porosityand permeability sandstone reservoir intervals become valid. Residual pore mainlyprimary intergranular pore and secondary dissolution pores. Mainly affected byreservoir sedimentation, digenesis and structure control.2. Xujiahe formation in the centre of Sichuan area. hydrocarbon source rocks ishigh, mainly organic type Ⅲ, to produce gas main, Ro value distribution at0.76%to1.59%range, have reached a high stage of maturity early evolution，Xujiahe naturalgas as a self-generated self-storage gas, natural gas from within Xujiahe blackshale-based coal-bearing strata.3. Foreland uplift to the main litho logic gas reservoir; foreland slope to construct -the main litho logic gas reservoir; foreland depression with litho logic gas reservoirsand gas reservoirs constructed mainly; foreland thrust belt in construct gas main.Section-two gas reservoirs are mainly developed in the depression zone and upliftzone; section-four gas reservoirs are mainly developed in the slope belt; section-sixgas reservoirs are mainly developed in the uplift zone, but most in the form ofsingle-well gas reservoir.4. Structural factors, source conditions, reservoir performance is the centre ofSichuan area region forming the main controlling factor, and the preservation of thecurrent structure and favorable conditions for the accumulation of secondary controlfactor. The development of fracture and crack control of oil and gas migration andaccumulation and redistribution, but more important is to control oil and gasproduction characteristics, inheritance and development of the ancient structures arefavorable for hydrocarbon accumulation zone. Meanwhile, the gentle slopes forelandbackground and wide distribution of low porosity and permeability sandstonereservoirs in Sichuan litho logic gas reservoir large area provides the basis for theformation of hydrocarbon source rocks Wide Duplex for hydrocarbon planar control alarge area of natural gas distribution, quality reservoir and fracture controlled gasenrichment yield.