大庆长垣北-断东葡Ⅰ油层组化学成岩作用对砂岩储层孔隙结构的影响

CHEMICAL DIAGENESIS INFLUENCE ON THE PORE TEXTURE OF SANDSTONE RESERVOIR OF PI OIL BEARING GROUP, EAST OF FAULT NORTH OF DAQING PLACANTICLINE

通过对650块砂岩样品铸体薄片偏光显微镜下观察,辅以粘土矿物X-射线衍射分析,电子探针,阴极发光显微照相,电子扫描显微镜,显微图象分析和压汞分析等手段,详细地研究了大庆长垣萨尔图油田北-断东地区葡Ⅰ油层组砂岩储层化学成岩作用与孔隙结构的关系,该区葡Ⅰ油层组砂岩属于湖泊浅水三角洲沉积体系中水下分流平原沉积,碎屑成分复杂,成熟度低,虽然现今埋深为950～1200m,但所经历的化学成岩作用对孔隙结构的改造效果却十分显著,其中体积分数1.1的亮晶方解石胶结作用可以使砂岩中粗喉(10～60"m)下降12.9％,渗透率降低1～2个数量级(/Jm^2),化学溶解作用是提高本区砂岩孔,渗的主要原因之一。它可以使砂岩的粗喉达26.3％,渗透率大于8flm^2。

Through analysis of 650 epoxy resin-pregnant thin sections of the sandstone under the binocular microscope and with the aid of the analysis methods of XRD, EPMA, CLP, SEM. MIA and MPA. this paper deals with the relationship between chemical diageneses and pore texture of the sandstone reservoir, PI oil bearing group at east of the fault on the north of Daqing placanticline. The sandstone reservoir in the area belongs to the subaqueous distributary plain in the depositional system of the lacustrine shallow water delta. The clastic component is complex and low in maturity. Although buried presently at a depth between 950 and 1 200 meters, it has suffered the chemical diageneses which have a great impact on the pore texture alteration. More than 10 percent (solid rock volume) calcite cement in the sandstone will make the relative volume of thick throat (10-60μm) decrease by 12. 9 percent and permeability by 1 or 2 magnituds. The chemical dissolution is one of the main factors to improve the porosity and permeability. It can enable the sandstone to have 26. 3 percent of the thick throat and more than 8 sq. micron of permeabiliy.