鄂尔多斯盆地苏里格气田致密砂岩储层孔隙类型及其渗流特征

The Seepage Characteristics of Different Pore Types of Tight Sandstone Gas Reservoir—— Taking the Southeast Area of Sulige Gas Field,Ordos Basin As an Example

为了探讨致密砂岩气藏不同孔隙结构的控制因素以及其内部流体渗流行为的差异,本文利用铸体薄片分析、高压压汞、核磁共振、气水相渗等一系列储层岩心分析资料从定性到定量的角度分别对鄂尔多斯盆地苏里格气田东南地区盒8段储层的孔隙类型、渗流特征进行研究,将储层按照溶蚀孔与晶间孔的相对含量划分为四类:晶间孔主导型储层、溶蚀孔—晶间孔混合型储层、晶间孔—溶蚀孔混合型储层、溶蚀孔主导型储层,并重点分析了四种储层类型所对应的可动流体、气水两相渗流特征。研究结果表明:成岩作用差异是导致储层具有不同孔隙结构类型的主要因素;不同孔隙类型储层之间的孔隙结构差异显著;从晶间孔主导型到溶蚀孔主导型储层,储层孔隙结构特征具有明显的改善趋势,可动流体饱和度增加明显,同时气、水两相干扰程度也逐渐增强,气相渗透率对含水饱和度的敏感程度也随之上升;晶间孔—溶蚀孔混合型储层是研究区广泛发育的储层类型,沉积微相对不同孔隙类型储层在平面上的分布起到了较大的控制作用。

Objectives： In order to investigate the controlling factors of different pore structures in tight sandstone gas reservoirs and the difference of internal fluid seepage behavior.Methods： Study the reservoir pore types and percolation characteristics of He 8 reservoir in the southeast area of Sulige from qualitative to quantitative perspective respectively by cast thin section,conventional mercury injection nuclear magnetic resonance and gas—water relative permeability. According to the relative content of dissolution pores and intergranular pores,the reservoir can be divided into four categories： intergranular pore,dissolutionpore— intergranular pore,intergranular pore— dissolution pore,dissolution pore,and also analyzed the movable fluid characteristics,gas—water relative permeability characteristics of the four kinds of reservoirs.Results： Diagenesis difference is the main factor leading to different pore structure types of reservoir. The pore structure of the reservoir with different pore types is significantly different. From intergranular pore dominant type to dissolution pore dominated reservoir,reservoir pore structure characteristics have obvious improvement trend,the saturation of movable fluid increases obviously,and the disturbance degree of gas and water gradually increases,the sensitivity of gas permeability on water saturation is also increasing.Conclusions： The type of intergranular pore and dissolution pore mixed reservoir is a widely developed reservoir type in the study area,the sedimentary microfacies play an important role in controlling the distribution of reservoirs in different pore types.