榆树林油田低渗透储层微观孔隙结构特征及渗流特性

Microporous structures and seepage regimes of the low-permeable reservoir beds in the Yushulin Oil Field, Heilongjiang

关键词:  低渗透油层  微观孔隙结构  榆树林油田  黑龙江

Key words:  low-permeable source bed  microporous structure  Yushulin Oil Field  Heilongjiang

摘要:

通过对榆树林油田压汞资料的分析,发现该油田的微观孔隙结构参数大部分与中高渗透油层的特征相似,其相对分选系数和结构系数随着渗透率的降低而增大,结构特征参数和孔喉平均半径随着渗透率的降低而减小。在毛管压力曲线上,其排驱压力高,孔喉细小。由于油层的低孔、低渗特性,油、水在孔隙介质中流动,呈现了非线性渗流特征,而且随着孔隙半径和渗透率降低,非线性渗流特征越来越明显。油水两相共同渗流时,束缚水饱和度、残余油饱和度以及共渗点饱和度均较高,而两相渗流范围较小,残余油下水相渗透率较低,最终驱油效率不高。

Abstract:

The analysis of the pressure mercury data indicates that most of the parameters for the microporous structures are similar to those of the moderate-to high-permeable reservoir beds in the Yushulin Oil Field, Heilongjiang. The relative sorting coefficients and structural coefficients tend to be increased in response to the decrease of the permeability while the structural parameters and average pore throat radii generally decrease in response to the decrease of the permeability. The capillary pressure curves also show that the driving pressures are inversely proportional to pore throat radii. The low porosity and permeability of the reservoir beds result in the nonlinear flows of the oil and water in the pore medium. Furthermore, this kind of nonlinear flows becomes conspicuous when the pore throat radii and permeability decline. The coexistence of oil and water in the nonlinear flows lead to the higher bound water saturation, residual oil saturation and co-vadose point saturation. The smaller extend of the vadose areas and lower permeability of the water below residual oil tend to cause the lower oil-driving efficiency.