苏里格气田东南部盒8段储层成岩作用研究及其孔隙演化模式定量分析

Diagenesis of He-8 Reservoir and Its Quantitative Analysis of Porosity Evolution Model in Southeast Sulige Gas Field

通过铸体薄片、扫描电镜、高压压汞、X线衍射、粒度分析及物性等资料,分析了苏东南地区主要的成岩作用类型及其对储层物性的影响。定量分析了各类成岩作用对储层孔隙的贡献率,结果发现胶结物晶间孔对该区储层孔隙贡献程度不可忽视,晶间孔对储集空间的贡献率平均为36.31%。随后对孔隙模式演化进行了定量分析,采用对不分选状况下未固结砂实测的初始孔隙度关系式恢复砂岩原始孔隙度,通过压实后粒间剩余孔隙度的恢复、压实后损失孔隙度的恢复、胶结作用引起的砂岩孔隙度降低和溶蚀作用引起孔隙度的增加幅度计算公式,实现了各成岩阶段孔隙度的定量分析。定量计算结果与实验室室内物性测试分析结果基本吻合,误差为2.5%,检验了研究方法的合理性,表明研究结果具有一定的可靠性。

Diagenesis refers to all physical, chemical and biological changes happened after deposition and before metamorphism. A variety of diagenesis plays a crucial role not only on reservoir porosity formation, preservation or destruction, but also on reservoir properties formation. Because the reservoir characteris- tics have an important effect on the gas yield of southeast Sulige area, the research of diagenesis is impor- tant to the fine reservoir evaluation and the forecast of southeast Sulige area. This study analyzes the main diagenetic type of southeast Sulige area and their impact on reservoir properties by casting thin sections, scanning electron microscope, high pressure Hg injection, X-ray diffraction, particle size analysis, physical properties and other information. Quantitative analysis is applied to evaluate the contribution rate of the various types of diagenesis on reservoir porosity. The results show that cement intercrystalline pore on the extent of the reservoir porosity contribution can be ignored in this region and the mean percentage of the total pore volume of intercrystalline porosity is 36. 31%. Afterward, the evolution of pore patterns is quantitatively analyzed under the regardless election situation using the Beard＇s formula. The initial porosi- ty formula unconsolidated sands is measured to restore the original sandstone porosity by the formulas of restoring the remaining intercrystalline porosity after compaction, recovering the loss of porosity after compaction, reducing of sandstone porosity due to cementation and increasing in porosity due to dissolu- tion. Quantitative porosity analysis for each diagenesis phase is achieved at the end. The quantitative re- sults and the laboratory test results are basically consistent, and the error is 2.5%, indicating that the quantitative analysis is reasonable and the results are reliable.