川西坳陷东坡沙溪庙组地层水对含水饱和度的影响  

Influence of formation water on water saturation:An example from Shaximiao Formation,western Sichuan Depression,Sichuan Basin

作　　者：颜学梅 苏锦义[1] 王玲辉[1] 周玲 YAN Xuemei;SU Jinyi;WANG Linghui;ZHOU Ling(Exploration and Development Research Institute,Sinopec Southwest Oil&Gas Company,Chengdu,Sichuan 610041,China;Labo-ratory of Geology Center,Sinopec Southwest Oil&Gas Company,Chengdu,Sichuan 610081,China)

机构地区：[1]中国石化西南油气分公司勘探开发研究院,四川成都610041 [2]中国石化西南油气分公司地质中心实验室,四川成都610081

出　　处：《天然气技术与经济》2022年第4期11-16,共6页Natural Gas Technology and Economy

摘　　要：为了准确计算储层含水饱和度,判断气藏含水特征,以四川盆地川西坳陷东坡侏罗系上、下沙溪庙组气藏为研究对象,分析了沙溪庙组气藏存在高电阻水层和低电阻气层的原因,指出利用单一的地层水电阻率计算得出的含水饱和度与实际测试结果之间有可能会出现一定的偏差,无法准确对气藏流体性质进行判别。研究结果表明:①川西坳陷东坡上、下沙溪庙组地层水特征差异大,水型总体以CaCl_(2)为主,含少量Na_(2)SO_(4)型和NaHCO_(3)型,地层水矿化度受保存条件及断层影响,在纵向上和平面上均存在着一定的差异;②川西坳陷东坡上、下沙溪庙组存在高、中、低3种不同类型的矿化度地层水,并且不同类型的地层水矿化度对地层水电阻率影响较大,采用单一的地层水电阻率估算含水饱和度将有可能导致计算结果与实际含水饱和度误差较大,影响对储层含气性的准确判断。结论认为,在地层水矿化度分类的基础上,按不同流动单元分别建立含水饱和度计算模型,通过不同地层水矿化度折算地层水电阻率得到的含水饱和度与实际测试结果吻合度更高。To accurately calculate water saturation in reservoirs and discriminate water-bearing characteristics,the gas reservoirs of both Upper and Lower Shaximiao Formation,east slope of western Sichuan Depression,Sichuan Basin,were taken as objectives to analyze the reason why both high-resistivity water layer and low-resistivity gas layer are presented in these reservoirs.And a certain deviation of water saturation was pointed out,which was individually obtained from unified formation-water resistivity and actual test result.So,it is hard to precise⁃ly discriminated the fluid properties in the reservoirs.Results show that(1)in the Upper and Lower Shaximiao Formation in this area,the formation-water characteristics vary greatly,with CaCl_(2)type as the main water type,and both Na_(2)SO_(4)and NaHCO_(3)types as the minor ones.The formation-water salinity is influenced by preserva⁃tion conditions and faults,representing a certain difference vertically and laterally;and(2)the formation water in the Upper and Lower Shaximiao Formation has three types of salinity(high,medium,and low),and various salin⁃ity types may substantially affect the formation-water resistivity.Therefore,when the unified formation-water resis⁃tivity is used to calculate the water saturation,an error between the calculated saturation and the real one is larger,which may affect an accurate judgement on the gas-bearing property in the reservoirs.In conclusion,a water-saturation calculation model shall be established for each flow unit based on typing of formation-water sa⁃linity,and the water saturation obtained from the formation-water resistivity,which is induced from formation-wa⁃ter salinity,is more accordant with the actual test result.

关 键 词：四川盆地 川西坳陷东坡 地层水分类 矿化度 含水饱和度 

分 类 号：P618.13[天文地球—矿床学]