致密砂岩气层近井带滤液侵入的电学响应

发布时间：2019-01-20 09:15

【摘要】：近年来,非常规天然气资源的勘探开发取得了显著成效。其中,致密砂岩气为天然气勘探与开发做出了重要的贡献,在天然气产量中所占比例日益提高。致密砂岩储层一般具有低孔低渗、高毛管压力、黏土矿物丰富等特征,在钻井完井过程中工作液滤液极易侵入储层,改变近井带流体分布,影响电学测井精度。因此开展致密砂岩电学参数对滤液侵入的响应关系研究,对测井精细解释与评价具有重要意义。以塔里木J区块致密砂岩气层为研究对象,分析了钻井完井液滤液侵入的地质因素,实验研究了气层在不同性质滤液侵入过程的电学参数响应特征。明确了研究区块致密砂岩气层地质特征。该气层孔隙结构复杂、天然裂缝发育、存在高矿化度地层水,其中黏土矿物以伊利石、伊/蒙间层矿物为主,岩石呈中间润湿。该气层在钻井完井作业过程中的工作液滤液侵入情况较为常见,影响了测井解释等工作。实验分析了致密砂岩在变矿化度流体、变含水饱和度、变有效应力条件下,岩心电阻率变化。随着流体矿化度的增加,岩心发生盐敏损害,平均孔喉半径减小,渗透率降低;地层因素F与胶结指数m随矿化度的增加而升高,当矿化度达到一定值时,上升趋势减缓。通过电阻增大系数确定电学参数a在1.2左右,饱和度指数n约为1.7。模拟了钻井液滤液滤液的侵入过程,并探究了侵入过程中岩心电阻率随含水饱和度变化的响应关系。在滤液侵入初期,岩心含水饱和度快速增加;当含水饱和度达到60%～70%时,增加幅度减缓至平稳。在侵入过程中,岩心电阻随着含水饱和度的升高而降低,降低趋势与含水饱和度的变化情况一致。计算了滤液侵入过程中井周含水饱和度及电阻率的变化。随着滤液的侵入,井周含水饱和度变化明显,在侵入带范围内,径向含水饱和度随着深度的增加而减小,电阻率随深度的增加而升高。
[Abstract]:In recent years, the exploration and development of unconventional natural gas resources have achieved remarkable results. Among them, tight sandstone gas makes an important contribution to natural gas exploration and development, and accounts for an increasing proportion of natural gas production. Tight sandstone reservoirs are generally characterized by low porosity and low permeability, high capillary pressure and rich clay minerals. During drilling and completion, the filtrate of the working fluid easily invades the reservoir, changes the fluid distribution in the near well zone, and affects the electrical logging accuracy. Therefore, it is of great significance to study the response of electrical parameters of tight sandstone to filtrate invasion for fine interpretation and evaluation of logging. Taking tight sandstone gas formation of Tarim J block as the research object, the geological factors of drilling and completion fluid filtrate intrusion are analyzed, and the electrical parameter response characteristics of gas formation in different nature of filtrate invasion process are experimentally studied. The geological characteristics of tight sandstone gas formation in the study block are clarified. The pore structure of the gas reservoir is complex and the natural fractures are developed. There is high salinity formation water in which the clay is mainly Illite and interlayer minerals and the rocks are wetted in the middle. During the drilling and completion of the gas reservoir, the working fluid filtrate invasion is more common, which affects the logging interpretation and so on. The change of core resistivity of tight sandstone under the condition of variable salinity fluid, water saturation and effective stress is analyzed experimentally. With the increase of fluid salinity, salt sensitive damage occurs in the core, the average pore throat radius decreases and the permeability decreases, while the formation factor F and cementation index m increase with the increase of salinity, and the upward trend slows down when the salinity reaches a certain value. The electrical parameter a is about 1.2 and the saturation exponent n is about 1.7. The intrusion process of drilling fluid filtrate was simulated and the response of core resistivity with water saturation was investigated. In the early stage of the filtrate invasion, the water saturation of the core increases rapidly, and when the water saturation reaches 60 ~ 70, the increase slows down to stable. During the intrusion, the core resistance decreases with the increase of water saturation, and the decreasing trend is consistent with the change of water saturation. The change of water saturation and resistivity around the well during the process of filtrate invasion is calculated. With the invasion of the filtrate, the water saturation changes obviously. In the range of the invasion zone, the radial water saturation decreases with the depth increasing, and the resistivity increases with the depth increasing.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE151

【参考文献】