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Research On Oil Accumulation Patterns Of Chang4+5and Chang6in Baihe Area Of Ordos Basin

Posted on:2015-10-21Degree:MasterType:Thesis
Country:ChinaCandidate:X X ZhouFull Text:PDF
GTID:2180330467471256Subject:Mineral prospecting and exploration
Abstract/Summary:PDF Full Text Request
Baihe area is located in west of North Shaanxi Slope in Ordos Basin. Through thepreparation of various types of maps, combining with regional geological data, it is known thatthe tectonic setting of the study area is a large west-dipping monoclinic, and this areadeveloped EW like nose uplift which is a ranked distribution. Chang6and Chang4+5belongto delta front facies and the underwater distributary channel sand bodies which overlap eachother are the main reservoir. The lithology is mainly fine-very fine-grained feldspathic lithicsandstone or lithic feldspathic sandstone. Chang6and Chang4+5reservoirs are low porosity,low permeability ones. The reservoir properties are poor, and belong to tight sandstonereservoir. The main factors of sharp decline in reservoir porosity and permeability includestrong compaction, pressure solution and high content of lithic fragments and feldspar whichare lower compressive strength in sandstone. Degree of reservoir heterogeneity is strong.The analysis of accumulation factors in study area show that source rocks are mainly theZhangjiatan black shale of Chang73which have large thickness, higher levels of organiccarbon content and chloroform bitumen "A" and middle levels of hydrocarbon generationpotential and hydrogen index. It belongs to a type Ⅱ kerogen. It is good to very good sourcerocks and has reached maturity. Hydrocarbon source rock enters into mature-high maturestage in the late Early Cretaceous to the Late Cretaceous. In Chang6and Chang4+5, thewidely development of underwater distributary channel sand bodies in delta front providepossibility for oil and gas reservoir formation. These sandstones near oil source, as one of themost favorable accumulation conditions. Abnormal pressure which is formed in Zhangjiatanblack shale of Chang73due to the combined effects of hydrocarbon generation and undercompaction provides the impetus for primary migration and secondary migration of oil and gas,but the buoyancy is limited. Based on the analysis of accumulation factor, the reservoirenrichment regularity of Chang6and Chang4+5in study area is summarized. The distributionof source rocks, the thickness and distribution of underwater distributary channel sand bodies,high-quality regional cap in the longitudinal direction jointly control the enrichment of reservoir.
Keywords/Search Tags:Ordos Basin, Baihe area, Chang4+5and Chang6, Accumulation elements, Accumulation patterns
PDF Full Text Request
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