徐家围子断陷登娄库组三段成岩模拟与致密砂岩储层类型预测

Diagenetic numerical modeling and tight sandstone reservoir types prediction of the Member 3 of the Denglouku Formation of the Xujiaweizi Fault Depression

为了预测松辽盆地徐家围子断陷深层登娄库组三段致密砂岩储层的类型和质量,根据深层的勘探实践和储层分析化验资料,将碎屑岩的成岩作用进一步细化为早成岩阶段A期、B期,中成岩阶段A1亚期,A2亚期、B1亚期、B2亚期,晚成岩阶段A期和B期3个阶段8个(亚)期,其中处于晚成岩阶段A期和B期的致密砂岩储层已不能产出工业气流。孔隙度和渗透率的统计结果表明,徐家围子断陷致密砂岩储层的物性主要受沉积相和成岩作用的影响,不同的沉积相和成岩相组合形成了致密砂岩3种类型的储层(Ⅱ、Ⅲ、Ⅳ类)。通过模拟古地温、镜质组反射率、甾烷异构化、粘土矿物转化和自生石英含量随时间的变化规律,模拟了成岩演化史、预测了成岩阶段和成岩相的平面分布。综合考虑沉积相和成岩作用对储层物性的影响,应用成岩作用数值模拟技术,通过成岩相分析,结合沉积相的研究成果,预测了登三段致密砂岩各种类型储层的平面分布特征。目前已发现的工业气流井主要位于Ⅱ、Ⅲ类储层分布的范围内。Ⅳ类储层中未发现工业气流,该类致密砂岩储层主要分布在晚成岩阶段A期—B期或处于滨浅湖相。引起成岩作用差异的主要因素是埋深。

To predict the reservoir type and quality of the tight sandstones of the Member 3 of the Denglouku Formation in the deep horizons of the Xujiaweizi Fault Depression,Songliao Basin,the diageneses of clastic rocks are divided into the period A of early diagenetic stage,the period B of early diagenetic stage,the sub-period A1 of middle diagenetic stage,the sub-period A2 of middle diagenetic stage,the sub-period B1 of middle diagenetic stage,the sub-period B2 of middle diagenetic stage,the period A of late diagenetic stage and the period B of late diagenetic stage on the base of the exploration results of the deep horizons and the reservoir testing data.The tight sandstone reservoirs in the period A and period B of late diagenetic stage can not produce commercial gas flows.As the result of statistical analysis of the reservoir porosity and permeability data show,the tight sandstone reservoir property or reservoir qualities in the Xujiaweizi Fault Depression are dominantly controlled by sedimentary facies and diageneses,and the combinations of different sedimentary facies and diagenetic facies form three kinds of different tight sandstone reservoirs,typeⅡ,typeⅢ,and type Ⅳ.By modeling the variation of paleotemperature,vitrinite reflectance,sterane isomerization,clay mineral transformation,and authigenic quartz formation with time,the diagenetic evolution history is modeled and the lateral distribution of the diagentic stage and diagentic facies are predicted.Considering the integrated effects of sedimentary facies and diageneses on the reservoir property,the tight sandstone reservoir types and quality of the Member 3 of the Denglouku Formation are predicted laterally by diagenetic numerical modeling and diagenetic facies analysis combining the sedimentary facies.At present the well producing commercial gas flows are mainly located in the reservoirs of typeⅡ or typeⅢ.No commercial gas flow is produced in the tight sandstone reservoirs of type Ⅳ which are mainly distributed in the period A and the period B of late diagenetic stage or located in the shallow lake facies.The main factor caused the diagenetic differences is depth.