Characteristics of Salt Lake Deposition and Significance for Oil-gas Exploration of Xingouzui Formation, Xingou oilfield, Jianghan Basin

摘要

Jianghan Basin is a typical Mesozoic-Cenozoic salt lake basin of East China, oil and gas reservoir with industrial utilization value was found in the Xingouzui Fm, Xingou Oilfield of this basin, the formation of which is closely related to the dolomite stratigraphy deposited in the salt lake. In order to explore the relationship between salt lake deposition with oil-gas reservoir and to get better understanding of the character of Jianghan Basin Salt Lake deposit to provide theoretical foundation for the exploration and development of the oil and gas resources. This paper, based on the elaboration study of the layer section core, combined with detection logging information and analysis test data, describes the salt lake deposit character according to the salt mineral species and profile thickness, makes an analysis of its formation mechanism, and discusses the salt lake deposit's indicating significance toward paleoclimate. The result suggests that the salt lake deposit of the research area demonstrate obvious feature of rhythmicity. Which shows in the alternating appearance of rhythmite composed by mudstone, dolomite, gypsum and rock salt. This kind of rhythmicity is a direct response of constantly changing of lake level rising-falling. The wide development of eury-thermal saline minerals such as calcite and dolomite, indicates that the palaeoclimate was arid to semi-arid in Jianghan Basin during the deposition of Xingouzui Formation in Paleogene. A complete salt rhythm can form a source-reservoir-seal assemblage, which has an important meaning for hydrocarbon generation, accumulation and preservation.