港深78井裂缝发育影响因素、成因及其在油气勘探中的意义

港深78井在油层厚度薄、油层埋藏深度大、物性差的情况下，日产600余t，创造了大港油田下第三系深层高产的新纪录。通过单井、构造、地应力、孔隙压力、负荷压力等的研究，油气高产和裂缝密切相关，地层的单层厚度、岩性、泥质含量、距主断层远近等项因素影响裂缝的发育程度。裂缝成因分构造成因和超压成因，构造成因裂缝形成早，多被充填闭合，超压成因裂缝形成晚，现今仍保持开启状态，有助于油气的高产。这一实例研究表明在沉积相带较差、砂岩厚度较薄、储层物性较差但异常高压发育的地区也可以形成富集高产油气田。

Controlling Factors and Causes of Fracture Formation in GS78 Area and its Significationin for Oil and Gas Exploration

Well GS78 is one of the high oil and gas production wells in Bohai Bay basins.It reached more than 600 m3/d,while its oil reservoir is thin,its burial deepth is large,and its reservoir properties is low.Its high production is related to fracture through well,structure,ground stress,pore fluid pressure,and load pressure research.Single stratum thickness,lithology,content of clay minerals and distance to major faults affected the development of fracture,There are mainly two causes of forming fracture,one is structure movement,the other is high pore fluid pressure,The structure fracture formed early,so they mostly closed.The high pore fluid pressure fracture formed later,so they keep to open.The case shows that enriched and high production oil and gas field can be found in areas where sedimentary facies is not so good,thickness of sand bodies is thin,reservoir properies is low,but overpressure developed.