基于不同砂体结构的宏观非均质性评价方法——以鄂尔多斯盆地合水地区长8油层组为例

Macro-heterogeneity evaluation based on different sand body structures: a case study of Chang 8 reservoir group in Heshui area, Ordos Basin

陈朝兵 付玲 南凡驰 冉婧 陈新晶 宗超伦 李昊远

CHEN Zhaobing FU Ling NAN Fanchi RAN Jing CHEN Xinjing ZONG Chaolun LI Haoyuan

西安石油大学 地球科学与工程学院, 西安 710065 陕西省油气成藏地质学重点实验室, 西安 710065 中国石油勘探开发研究院, 北京 100083 中国石油 长庆油田分公司 对外合作部, 西安 710200 中国石油 长庆油田分公司 第六采油厂, 西安 710200 中国石油 华北油田分公司 第五采油厂, 河北 任丘 052360

School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China Shaanxi Key Laboratory of Petroleum Accumulation Geology, Xi'an, Shaanxi 710065, China Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China Department of Foreign Cooperation, PetroChina Changqing Oil Field Company, Xi'an, Shaanxi 710200, China No.6 Oil Production Plant, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710200, China No.5 Oil Production Plant, PetroChina Huabei Oilfield Company, Renqiu, Hebei 052360, China

宏观非均质性是影响油田开发效果的重要因素之一，尤其是对于砂体结构复杂的三角洲沉积环境，非均质性严重制约了油藏的高效开发。以鄂尔多斯盆地合水地区上三叠统延长组长8油层组为例，通过露头剖面观测、岩心观察、测井及生产动态资料，分析砂体结构类型及特征，建立了储层宏观非均质性评价方法。研究区长8浅水三角洲发育连续叠加型、间隔叠加型、侧向单层型和砂泥互层型等4种砂体结构。层内夹层及层间隔层导致砂体空间连续性降低，连续叠加型的隔夹层发育程度及渗透率非均质性最弱，其宏观非均质性最弱；其次是间隔叠加型和侧向单层型；砂泥互层型的宏观非均质性最强。选取夹层密度Dk、夹层频率Pk和储层质量系数RQI构建层内非均质性评价指数N，N指数能够反映不同砂体结构下的单砂体层内流体驱替特征及含水率变化。选取砂岩百分比Sn、单位厚度层间砂体层数T等参数构建层间非均质性评价指数J，J指数是评价和预测油井产液强度的较好度量。因此，层内非均质性指数N和层间非均质性指数J能够用于油藏的宏观非均质性评价。

Macro-heterogeneity is one of the important factors affecting oilfield development, especially for deltaic sedimentary environments with complex sand body structures. The structure type and characteristics of sand bodies were analyzed for Chang 8 reservoir group (the eighth member of Upper Triassic Yanchang Formation) in the Heshui area of the Ordos Basin. An evaluation method for reservoir macro-heterogeneity was established based on outcrop and core observation, and logging and production performance data. Four sand body structures in the Chang 8 shallow water delta were identified, including continuous superposition, interval superposition, lateral single layer and sand-mud interbedded types. The interlayers and restraining barriers lead to the decrease of the spatial continuity of sand body. Generally, the development degree of interlayers and permeability heterogeneity of the continuous superimposed type is the weakest, and the macro-heterogeneity is the weakest, followed by the interval superposition and the lateral single layer types, while the macro-heterogeneity of sand-mud interbedding type is the strongest. The interlayer density (DK), interlayer frequency (Pk) and reservoir quality coefficient (RQI) were selected to construct the evaluation index (N) of intraformational heterogeneity. The N index can reflect the fluid displacement characteristics and water content change of single sand body within different sand body structures. The evaluation index J of interlayer heterogeneity was constructed by selecting parameters such as the percentage of sandstone (Sn) and the number of interlayer sand layers per unit thickness (T). The J index is a good measure to evaluate and predict the fluid production strength of oil wells. Therefore, the intraformational heterogeneity index (N) and interlayer heterogeneity index (J) can be used to evaluate the macro-heterogeneity of reservoirs.

国家自然科学基金 41802140;陕西省自然科学研究基础计划项目 2019JQ-257;刘宝珺地学科学基金 DMSM2019007;国家科技重大专项 2016ZX05050006

https://doi.org/10.11781/sysydz202102242