Chemical Distribution of Formation Water in Yanchang 6 Oil Formation in Shuanghe Area,Ordos Basin
The relationship between oil and water in tight reservoirs is complicated,so the chemical composition and distribution of formation water are of great significance to guide tight oil exploration.Based on this,the relationship between formation water chemical composition,salinity,water chemical characteristic parameters,sedimentary microfacies,effective thickness and productivity of Chang 6 oil formation in Shuanghe area was deeply studied.The research shows that the type of formation water in Shuanghe area is mainly CaCl2 type,and the salinity of formation water is mainly distributed in 2 201.2～153 670.9 mg/L,with an average of 53 947.2 mg/L.The oil saturation decreases with the increase of the salinity before the salinity value of 5 000 mg/L,while the oil saturation increases with the increase of the formation water salinity after the salinity value of 50 000 mg/L.This is because higher sa-linity represents good preservation conditions,conducive to long-term large-scale accumulation of oil and gas,so the oil saturation is high.However,when the salinity of the target layer is in the relatively low range of 10 000～20 000 mg/L,it mainly corresponds to the composite sand body composed of 3～5 m thin layer single sand body,so the oil saturation is relatively high.According to the analysis,the characteristics of salinity,sodium chloride coefficient and magnesium calcium coefficient of the target layer all indicate that the tar-get layer is in a relatively closed sedimentary environment,which is conducive to the preservation of oil and gas.These hydrochemical parameters are significantly correlated with tight oil reservoir accumulation and productivity.
Ordos BasinShuanghe areaChang 6 oil formationformation waterwater chemical parametersdistribution law
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维普
