伊朗SA 油田SarvaK 油藏大幅度倾斜油水界面成因探讨

Genesis of large-amplitude tilting oil-water contact in Sarvak Formation in South Azadegan Oilfield, Iran

杜洋 衣英杰 辛军 陈杰 崔燚 童明胜 欧阳诚 王维斌

Du Yang Yi Yingjie Xin Jun Chen Jie Cui Yi Tong Mingsheng Ouyang Cheng Wang Weibing

西南石油大学 地球科学与技术学院, 成都 610051 2. 川庆钻探工程公司 地质勘探开发研究院, 成都 610000 3. 中国石油勘探开发研究院, 北京 100083 4. 中油国际 伊拉克分公司, 迪拜 999041

School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610051, China 2. Geology and Exploration Research Institute of CCDC, CNPC, Chengdu, Sichuan 610500, China 3. Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China 4. Iraq Branch Company, CNPC, Dubai 999041, UAE

针对伊朗SA油田上白垩统Sarvak油藏所具有的大幅倾斜油水界面异常油藏特征,对其成因进行探讨。对可能造成油水界面倾斜的水动力和储层非均质性进行的分析表明,两者均不是造成该现象的原因。在调研区域构造背景基础上,运用地震层拉平技术对油田不同时期古构造圈闭进行恢复,综合各成藏要素特征分析,认为扎格罗斯构造运动导致的圈闭超晚期调整为本区油水界面倾斜主要原因。古新世晚期SA油田Sarvak层即形成北高南低、与现今构造形态相反的古背斜圈闭油藏;新近纪扎格罗斯造山运动导致圈闭形态发生二次改变,南部原古构造低点以"翘翘板"方式大幅度向上抬起,形成新的次生圈闭,演变为现今两构造高点,南高北低构造形态。圈闭条件的改变打破了原古油藏动力平衡,导致烃类流体向南部次生高点圈闭的二次运移调整,直到目前仍处于调整过程中。现今大幅倾斜油水界面为古油藏尚未调整完毕所显示的特征,油藏为非稳态油藏。

The Sarvak reservoir of the South Azadegan Oilfield in Iran is a thick, block-like limestone reservoir of slack shelf sea deposition. The oil-water contact (OWC) of the reservoir is characterized as a large-amplitude one tilting from north to south. Hydrodynamic force and reservoir heterogeneity were studied, indicating that neither of which were the causes for the tilted OWC of the Sarvak reservoir. By investigating the evolution of areal tectonic setting, utilizing a formation flattening technique to recover the paleo-structure of different geologic stages, and combining with accumulation factor analysis, it was determined that the adjustment of traps after the Zagros orogeny led to the tilted oil-water contact. A paleo-trap which decreased from north to south (reversed from the present situations) formed in the Sarvak Formation in the SA Oilfield after the late Paleocene. The Zagros orogeny during the Neogene caused the adjustment of the trap, and the former low point in the south uplifted significantly and gave birth to a new secondary trap. As a result, the present tectonic setting with two high points (higher in the north and lower in the south) was formed. The balance in the paleo-trap was broken, and hydrocarbon migrated to the secondary trap in the south and was still adjusting now. The large-amplitude tilting oil-water contact showed that the paleo-reservoir was still adjusting and unstable.

中国石油天然气集团公司重大科技专项"中东地区碳酸盐岩油藏整体优化部署及提高采收率技术研究与应用"(11.2011E-2501.X.01)资助。

https://doi.org/10.11781/sysydz201502187