鄂尔多斯盆地靖边气田高桥区块马五41段白云岩储层建设性埋藏成岩作用及意义

受古岩溶作用的影响，鄂尔多斯盆地靖边气田高桥区块形成了层位较稳定的溶蚀孔洞白云岩储层。利用钻井岩心、铸体薄片、阴极发光及地球化学手段等，对研究区马五41段白云岩储层埋藏环境下建设性成岩作用进行了系统研究。研究表明，区内埋藏环境下建设性成岩作用有埋藏白云石化作用、埋藏溶解作用、裂缝作用等。研究区晶粒白云岩C、O同位素比值与奥陶纪海水的C、O同位素值相比明显偏负，表明地层经历了埋藏白云石化作用，埋藏白云石化作用使得岩石体积缩小、岩石孔隙度有所增加，有利于晶间孔的形成。埋藏溶解作用可形成大量的溶蚀孔、洞、缝等储集空间，为油气的储集成藏提供了有利的场所。裂缝的发育增加了溶蚀孔洞的连通性，有效地提高了储层的孔隙度与渗透率。上述3种建设性成岩作用相互叠加配合，使得裂缝与原本存在的孔隙配套，对良好油气储集空间的形成起了决定性控制作用。

Constructive burial diagenesis and significance of dolomite reservoir from the Ma541 member in Gaoqiao area, Jingbian gas field, Ordos basin

Influenced by paleokarst, stable porous dolomite reservoir layer was formed in Gaoqiao area, Jingbian gas field, Ordos Basin. In this paper, the authors conducted systematical research by means of well core, cathodoluminescence image and geochemistry of burial diagenesis of the Ma541 member in Gaoqiao area. The results indicate that the constructive diagenesis in a burial environment consists of burial dolomitization, burial dissolution and fracture effect. The carbon and oxygen isotope values of crystal grain dolomite are obviously negative compared with those of the Ordovician sea water. So it is obvious that the strata experienced burial dolomitization. The burial dolomitization which reduced the volume of the rock and increased the porosity was conducive to the formation of intergranular pore. The burial dissolution caused a series of storage spaces with holes and seams, and resulted in meaningful places for oil and gas reservoir. In addition, the development of fissures increased the connectivity of the pores and effectively increased the porosity and permeability of the gas reservoir. These three kinds of constructive diageneses were superimposed upon each other and the cracks linked the existing pore. This pore-hole-seam-crack system seems to have been a decisive control function for the formation of oil and gas storage reservoir.