混合泥质砂岩通用电阻率模型研究

基于层状泥质与分散泥质砂岩的并联导电,而分散泥质砂岩导电性等效于分散粘土和地层水为一种导电液体的纯砂岩,并考虑到在低地层水电导率(Gw)范围内分散粘土电导率(Ccl)随Gw增大而增大,建立了混合泥质砂岩通用电阻率模型.通过对该模型的影响因素分析,发现泥质分布形式对模型计算的含水饱和度有很大影响;只有Ccl变化时,地层电导率(G1)与有效含水饱和度(Sw)关系曲线的曲率相近;随Sw增大,胶结指数m对Ct与S关系曲线的影响增大,而饱和度指数n对Ct与Sw关系曲线的影响减小.通过2组分散泥质砂岩岩样实验测量数据和1组层状泥质砂岩测井资料的测试,表明该模型既适用于分散泥质砂岩地层解释又适用于层状泥质砂岩地层解释,给出的电阻率模型为通用电阻率模型.利用建立的混合泥质砂岩通用电阻率模型对海拉尔盆地高泥地区的苏1、苏3井进行处理,并将模型计算的含水饱和度与试油结果进行对比,结果表明模型计算的含水饱和度是合理的.本模型适用于高泥地区的泥质砂岩地层解释.

On Generalized Resistivity Model for Laminated and Dispersed Shaly Sands

Based on the parallel conductance assumption between laminated shaly pattern and the dispersed shaly sand pattern, and the assumption under which the dispersed shaly sand is conductively equivalent to the clean sand with dispersed clay and water is taken as a conductively equivalent fluid, and dispersed clay conductivity( C cl ) increases as water conductivity( C w)increases in low water conductivity, a generalized resistivity model is established. It is pointed out that shale distribution largely affects water saturation predicted by this model. The curvatures of the curves between total formation conductivity ( C t) and effective water saturation ( S w) are about the same when only C cl varies. As S w increases, the effect of cementation exponent ( m ) on the relation between C t and S w increases while the effect of saturation exponent ( n ) on that decreases. Rock sample data in dispersed shaly sands and logging data of laminated shaly sands show that this model may be applied not only in dispersed shaly sands but also in laminated shaly sands. The proposed resistivity model can be taken as a generalized resistivity model. Log data of well SU-1 and SU-3 in the very shaly formation in Hailaer basin are interpreted with the model proposed in the paper, then the calculated water saturation with test results is compared. The result shows that the water saturation calculated with the model is right, so the model proposed in the paper can be applied to very shaly sand.