鄂尔多斯盆地中东部奥陶系马家沟组四段储层特征及主控因素

Reservoir characteristics and main controlling factors of the fourth member of Ordovician Majiagou Formation in the central and eastern Ordos Basin

牟春国 许杰 古永红 贾建鹏 王文雄 谭秀成

MOU Chunguo XU Jie GU Yonghong JIA Jianpeng WANG Wenxiong TAN Xiucheng

中国石油 长庆油田分公司 油气工艺研究院，西安 710018 低渗透油气田勘探开发国家工程实验室，西安 710018 油气藏地质及开发工程国家重点实验室(西南石油大学)，成都 610500 中国石油集团 碳酸盐岩储层重点实验室 西南石油大学研究分室，成都 610500 中国石油 长庆油田分公司 勘探事业部，西安 710018

Oil and Gas Technology Research Institute, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710018, China National Engineering Laboratory for Low Permeability Oil and Gas Field Exploration and Development, Xi'an, Shaanxi 710018, China State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China Research Branch of Southwest Petroleum University, Key Laboratory of Carbonate Reservoirs of China National Petroleum Corporation, Chengdu, Sichuan 610500, China Exploration Division, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710018, China

近期勘探实践表明，鄂尔多斯盆地中东部奥陶系马家沟组四段豹斑状白云岩储层具有良好的勘探开发潜力。为此，基于钻井岩心、岩石薄片和分析化验资料，解析了该层段的储层特征及主控因素。结果表明：(1)马四段储层的储集岩类主要包括豹斑状云质灰岩、豹斑状灰质云岩、晶粒云岩和凝块云岩，储集空间类型以晶间(溶)孔为主，含少量格架孔和微裂缝。(2)研究区储集层整体表现为低孔—中低渗孔隙型储层，其中储集性能以豹斑状灰质云岩和晶粒云岩最佳且分布范围广，是区内最优质的储集岩类。而豹斑状云质灰岩发育规模较大，储集性能整体较差，凝块云岩储集性能较好，但发育频率较低。盆地中东部马四段储层发育主要受沉积微相、生物扰动、白云石化作用以及早成岩期岩溶作用综合控制：有利沉积微相是储层发育的物质基础，控制储层平面横向分布；生物扰动作用有利于白云石化作用；白云石化作用是储层形成的关键，有利于储层孔隙的保存；早成岩期岩溶作用对储层质量改善有着重要贡献。马四段有利储层纵向上主要位于高频向上变浅序列的中上部；平面上，主要集中在研究区西侧乌审旗—靖边—志丹一线以及东侧的神木、米脂两个相对独立的区域。

Recent exploration practice shows that the leopard porphyry dolomite reservoir in the fourth member of Ordovician Majiagou Formation in the central and eastern Ordos Basin has good exploration and development potential. Therefore, based on drilling cores, rock slices and analysis and laboratory data, the reservoir characteristics and main controlling factors of this section were analyzed. The results show that: (1) The reservoir rocks of the fourth member of Majiagou Formation mainly include leopard porphyry dolomitic limestone, leopard porphyry limy dolomite, crystalline dolomite and clotted dolomite, and the reservoir space types mainly consist of intergranular (dissolution) pores, with a small amount of lattice pores and microcracks. (2) The reservoir in the study area is generally characte-rized by low porosity and medium-low permeability pore type reservoir, in which leopard porphyry limestone dolomite and crystalline dolomite are the best reservoir rocks with wide distribution range. However, leopard porphyry dolomitic limestone is developed on a large scale, with poor reservoir performance as a whole, while clotted dolomite has good reservoir performance, but its development frequency is low. The reservoir development in the fourth member of Majiagou Formation in the central and eastern Ordos Basin is mainly controlled by sedimentary microfacies, bioturbation, dolomitization and early diagenetic karstification: as the material basis for reservoir formation, favorable sedimentary microfacies control the horizontal distribution of reservoirs; bioturbation is for dolomitization; dolomitization is the key to reservoir formation, which is conducive to the preservation of reservoir pores; early diagenetic karstification has an important contribution to the improvement of reservoir quality. In the longitudinal, the favorable reservoirs in the fourth member of Majiagou Formation are mainly located in the middle-upper part of the high-frequency upward shallowing sequence; on the plane, the favorable reservoirs are mainly concentrated in the line of Wushen Banner-Jingbian-Zhidan in the west and the two relatively independent areas of Shenmu and Mizhi in the east of the study area.

中国石油集团公司上游领域基础性前瞻性项目 2021DJ0501

https://doi.org/10.11781/sysydz202304780