The Characteristics Of Palaeokarst Reservoir Of Ma5₄¹in Gaoqiao Area Of Jingbing Gas Field

The reservoir of ma5₄¹in gaoqiao area of Jingbian gas field is the expansion area for theJingbian gas field weathering crust gas reservoir, which is the typical palaeogeomor-phology（formation）-lithologic traps gas reservoir. In recent years, the exploration of ma5₄¹inGaoqiao area has made progress constantly. It is not complete that the work had developed sofar，because there are several problems in the trap type of gas reservoir, the delineation of gastrap area and the control factors of gas reservoir. Therefore, developing the gas reservoirsfactors controlling reservoir research of ma54’, eapecially, it is important to study thedevelopment characteristics and distirbution of karst reservoir, ultimately, to make thecontirbution guiding the exploration in gas field.The research has been done systematically in the characteristics of lithology, character-irstics of geochemical, structure of pore, type of karst, karst zoning, environment of diageneticand diagenesis in Gaoqiao area, based on regional geological setting, cores, flakes, logging,analysising of geochemical data, combined with the results of previous studies; recoveredpaleo-karst landforms in studied area based on the residual thickness of the weathering crustand the thickness of weathering crust overlying strata; analyzed the controlling factors of karstarea. The result of study indicate: the lithology of karst reservoir is dolostone, followed bylimestone, rare the evaporites and tuff, developmental dissolution pores, holes，sewing，andintergranular porosity; carbon and oxygen isotope has obviously negative bias, the87S6r/8Srincreased; there are2types of the second level: karst tableland, karst slopes; the palaeokarst instudied area is divided into syngenesis karst, hypergene karst and buiral karst, and the mostimportant is hypergene karst; paleo-karst zone can be divided into vertical seepage andhorizontal subsurface flow; dissolution and reflux dolornitization are constructive to thereservoir pore development, while dedolomitization and compaction-pressure solution aredestructive; it’s mainly affected by the development of karst reservoir sedimentary facies，diagenetic effects and ancient karst landform factors control, according to the analysis of themain controlling factors of gas accumulation, through comprehensive research on gas accumu?lation conditions and evaluation, favorable reservoir distirbution areas in Gaoqiao area are Tao6, S63-S328, S223-S225and S50well field...