杭锦旗地区J58井区下石盒子组气水分布及其控制因素

Gas and water distribution and its controlling factors of Xiashihezi Formation in J58 well area,Hangjinqi area

J58井区下石盒子组是杭锦旗地区致密砂岩气勘探开发的重点层段,目前对其气水分布关系以及影响因素认识不清,极大地制约了天然气的有效开发。在研究区地质特征研究的基础上,通过对该区30余口井的测井资料、试气资料及地层水化学资料的综合分析,弄清了J58井区的气水分布规律及主控因素。结果表明:该区地层水矿化度为24 176～76 917 mg/L,地层水水型为CaCl_2型,反映了地层水封闭性好,有利于天然气的聚集和保存。纵向上气水分异不明显,气水层连续性差,多数为气水同层,盒1段气层较发育。平面上气层集中分布于河道砂体连片区,水层主要位于砂体边部。气水分布主要受生烃强度、沉积相、有效砂体厚度及含砾砂岩厚度等因素控制,气层主要分布在生烃强度大于15亿m^3/km^2的区域,储集层距烃源岩越近,气层相对更发育;沉积相、有效砂体厚度和含砾砂岩厚度进一步控制着气产量及气、水层的展布范围。该研究成果对确定研究区天然气有利靶区具有指导作用。

Xiashihezi Formation in J58 well area is a key section of tight sandstone gas exploration and development in Hangjinqi area.At present,the distribution of gas and water and its influencing factors are not clearly understood,which greatly restricts the effective development of natural gas.Based on the study of geological characteristics of the study area,through comprehensive analysis of logging data,gas test data and formation water chemistry of more than 30 wells in this area,the distribution law of gas and water and the main controlling factors in J58 well area were defined.The results show that the salinity of formation water in this area is 24 176-76 917 mg/L,and the formation water types are all CaCl2,which reflects that the formation water is well sealed and conducive to the accumulation and preservation of natural gas.Vertically,gas and water differentiation is not obvious,the continuity of gas and water layer is poor and most of them are coexisting gas and water zone,and the gas reservoir of He 1 member is more developed.In the plane,gas layers are concentrated in the channel sand bodies,while water layers are mainly located at the edge of sand bodies.The distribution of gas and water is mainly controlled by hydrocarbon generating intensity,sedimentary facies,effective sand body thickness and pebbly sandstone thickness.Gas reservoirs are mainly distributed in areas where hydrocarbon generation intensity is greater than 15×10^8 m^3/km^2.The closer the distance between reservoirs and hydrocarbon source rocks,the more developed the gas reservoirs are.Sedimentary facies,effective sand body thickness and pebbly sandstone thickness further control gas production and the distribution range of gas and water layers.The results of this study have a guiding role in determining the favorable target areas for natural gas in the study area.