致密砂岩储层电性特征分析

为了弄清致密砂岩储层复杂的电性特征,以高分辨率阵列感应资料为基础,结合核磁测井、岩心微观分析资料及试气成果,对鄂尔多斯盆地东缘L区块二叠系上石盒子组致密砂岩储层的电性特征进行了分析,找出了导致电阻率值存在差异以及储层具有不同侵入特征的原因。研究表明：致密砂岩储层流体性质并不是电阻率值存在差异的主控因素,低电阻率主要是孔喉边缘黏土矿物的束缚水与可联通孔隙喉道内的毛管水共同导电造成的,中—高电阻率与孤立孔隙无法导电有关;侵入特征与含气性及喉道的沟通能力有关,低电阻率负差异储层是含气性与优质孔隙结构的指示,低电阻率无差异为片状喉道导致的不动水导电和毛管阻力及黏土矿物阻止钻井液侵入有关,中—高电阻率无差异与孤立孔隙无法导电及无法侵入有关。导致地层出现这种电性特征是沉积作用、成岩作用及后期成藏的共同影响的。该研究成果对指导研究区致密储层的勘探开发具有重要意义。

Analysis of electrical characteristics of tight sandstone reservoirs

In order to clarify the complex electrical characteristics of tight sandstone reservoirs,the electrical characteristics of tight sandstone reservoirs of Permian upper Shihezi Formation in L block in the eastern margin of Ordos Basin were analyzed based on high resolution array induction data,combined with nuclear magnetic logging,core micro-analysis data and gas testing results,and the causes of resistivity differences and different intrusion characteristics were found out.The results show that fluid property of tight sandstone reservoir is not the dominant factor for the difference of resistivity.The low resistivity is mainly caused by co-conductivity of bound water caused by clay minerals at the edge of pore throat and capillary water in the connectable pore throat.The medium and high resistivity is mainly related to the non-conductivity of isolated pore.The invasion characteristics are mainly related to gas-bearing property and the communication ability of throat.Low resistivity negative difference reservoir is indicator of gas-bearing property and high-quality pore structure.No difference in low resistivity is related to the immovable water conductivity caused by flaky throat,capillary resistance and clay minerals preventing drilling fluid invasion.No difference between medium and high resistivity is related to the inability of conduction and invasion of isolated pore.It is the common influence of sedimentation,diagenesis and later accumulation that leads to the formation of such electrical characteristics.The research results are of great significance for guiding exploration and development of tight reservoirs in the study area.