玛2井区百口泉组砂砾岩储层可动流体赋存特征及主控因素

Occurrence characteristics and control factors of movable fluids in Baikouquan Formation glutenite reservoirs in Ma 2 Block

砂砾岩储层孔喉结构非均质性强、流体赋存规律复杂,制约单井产能及油藏开发效果。选取玛2井区百口泉组典型砂砾岩岩心,利用低场核磁共振技术进行储层可动流体离心实验,定量表征不同孔喉尺度的可动流体分布特征,分析可动流体主控因素。结果表明:百口泉组砂砾岩储层可动流体参数差异较小,其中T2截止值介于1.86~6.69 ms,平均为4.02 ms;可动流体饱和度为44.30%~54.88%,平均为48.38%;可动流体孔隙度为1.86%~6.69%,平均为3.95%。砂砾岩岩心实验的最佳离心力介于0.92~0.97 MPa,最佳离心状态下较大孔喉流体动用程度较高,束缚流体主要赋存于较小孔喉。孔隙度、渗透率与可动流体饱和度呈正相关关系,孔喉连通性越好,物性越好,可动流体含量越高;黏土矿物填充或遇水膨胀减小孔隙空间或堵塞喉道,造成束缚流体含量增加。该结果为认识砂砾岩油藏储层特征及渗流规律提供支持。

Sandy conglomerate reservoirs have the characteristics of strong heterogeneity of pore throat structure and complex fluid occurrence mechanism,which restrict the product-ivity of single wells.In order to reveal the microscopic occurrence characteristics of fluid in gluteni、e reservoirs,taking the Baikouquan Formation in well Ma 2 as a case,typical glutenite core samples were selected.The microscopic pore-throat characteristics of Baikouquan Formation reservoirs were qualitatively evaluated by scanning electron microscopy(SEM) and high-pressure mercury intrusion(HPMI) tests.The NMR movable fluid test was carried out to quantitatively characterize the distribution characteristics of movable fluid at different pore-throat scales,and to clarify the key control factors of movable fluid.The results show that the difference of movable fluid parameters in the glutenite reservoir of Baikouquan Formation is small.The T2 cutoff values of Baikouquan Formation range from 1.86 to 6.69 ms,with an average of 4.02 ms.The movable fluid saturation ranges from 44.30% to 54.88%,with an average of 48.38%.The movable fluid porosity ranges from 1.86% to 6.69%,with an average of 3.95 %.The best centrifugal force exists in the centrifugation experiment of glutenite core samples,and the best centrifugal force is between 0.92and 0.97 MPa.Under the optimal centrifugal force,the fluid in the larger pore throats is almost completely used,and the main storage space for the bound fluid is the smaller pore throats.The porosity and permeability are positively correlated with the movable fluid saturation of the overall pore throat.The correlation analysis between the pore-throat characteristic parameters and the movable fluid saturation shows that the pore-throat connectivity and sorting are good,and the fluid in the pore-throat has the high seepage capacity.The clay minerals fill or swell with water to reduce the pore space or block the throat,causing an increase in bound fluid content.The research provides theoretical support for further understanding the reservoir characteristics and seepage law of the conglomerate reservoir.