| 层序格架约束下沉积、成岩作用对岩石物性的控制：以中东A 油田白垩系Mishrif 组为例 |
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| 引用本文： | 李峰峰,郭 睿,宋世琦.层序格架约束下沉积、成岩作用对岩石物性的控制：以中东A 油田白垩系Mishrif 组为例[J].高校地质学报,2021,27(4):432-443. |
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| 作者姓名： | 李峰峰 郭 睿 宋世琦 |
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| 作者单位： | 1. 中国石油勘探开发研究院，北京 100083；
2. 中国石油大学（北京）地球科学学院，北京 102249 |
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| 摘 要： | 厚层块状碳酸盐岩储层垂向非均质性强，层间产液不均衡。为明确储层和隔夹层形成机理和展布规律，以中东A油田白垩系Mishrif组为例，在层序格架的控制下，研究沉积作用和成岩作用对岩石物性的影响。结果表明：Mishrif组内部发育6个四级层序旋回，海平面升降控制了沉积环境演变，并对早期成岩环境具有重要的影响，根据水体能量和成岩作用性质可分为5种沉积—成岩组合：（1）高能沉积环境+建设性成岩作用，滩体发生非选择性溶蚀作用，大幅提高岩石物性形成优质储层；（2）高能沉积环境+破坏性成岩作用，滩体发生不同程度的胶结作用，降低岩石原始物性形成差储层或物性隔夹层，物性隔夹层隐蔽性强，识别困难，加剧了储层的非均值性；（3）低能沉积环境+建设性成岩作用，潟湖、开阔浅海及滩后发生选择性溶蚀和白云化作用，有效改善岩石物性，主要形成差储层；（4）低能沉积环境+破坏性成岩作用，潮湿气候条件下，潟湖相岩石发生压实作用和胶结作用，层序顶部发育炭质泥岩，形成暴露胶结炭化带。干旱和潮湿气候交替条件下，潟湖相岩石遭受多期风化—淋滤，形成致密胶结的角砾岩；该类沉积—成岩组合通常形成于低位体系域，形成稳定分布隔夹层；（5）低能沉积环境+弱成岩作用，岩石原始物性较差，灰泥含量高，后期未发生明显的成岩改造，多形成岩性隔夹层。Mishrif组在多期层序旋回控制下，沉积—成岩组合不断变化，物性隔夹层主要分布在优质储层内部，厚度较薄，规模较小，分布不稳定；岩性隔夹层与差储层相伴生，不同环境中的岩性隔夹层分布稳定性差异较大，致密胶结带通常分布稳定，将地层划分为不同的开发层系。
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| 关 键 词： | 碳酸盐岩 隔夹层 Mishrif组 层序 沉积作用 成岩作用 |
Impacts of the Sedimentation and Diagenesis on Reservior PhysicalProperty under the Control of Sequence: A Case Study of theCretaceous Mishrif Formation,A Oilfield in the Middle East |
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| LI Fengfeng,GUO Rui,SONG Shiqi.Impacts of the Sedimentation and Diagenesis on Reservior PhysicalProperty under the Control of Sequence: A Case Study of theCretaceous Mishrif Formation,A Oilfield in the Middle East[J].Geological Journal of China Universities,2021,27(4):432-443. |
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| Authors: | LI Fengfeng GUO Rui SONG Shiqi |
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| Institution: | 1. Research Institute of Petroleum Exploration & Development，PetroChina, Beijing 100083, China；;
2. College of Geosciences, China University of Petroleum (Beijing) , Beijing 102249, China; |
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| Abstract: | Strong vertical heterogeneity of thick carbonate reservoirs that led to disproportionate production. To clarify the mechanism and distribution of reservoirs and interlayers, taking based on a case study in the Cretaceous Mishrif Formation of A oilfield in the Middle East, the effects of sedimentation and diagenesis on reservoir physical properties were studied under the control of sequence stratigraphy frameworks. The results showed that there were 6 quaternary sequences in the Mishrif Formation, and the sea level controlled the evolution of the sedimentary environment, and had an important impact on the early diagenetic process. On the basis of water energy and sedimentation diagenesis characteristics, it could be divided into 5 combinations (1) High-energy environment+constructive diagenesis. The non-selective dissolution of the shoal greatly improved the reservoir physical properties of the rock forming high-quality reservoirs. (2) High-energy environment+destructive diagenesis. Different degrees of cementation occurred on the shoal, reducing the physical properties of the rocks and forming poor reservoirs or physical interlayers. Which were highly hidden and difficult to be identified, increasing the reservoir heterogeneity. (3) Lowenergy environment+constructive diagenesis. Selective dissolution and dolomitization occurred in lagoons, open shallow seas, and the back shoal, effectively improving rock physical properties, and mainly forming poor reservoirs. (4) Low-energy environment +destructive diagenesis. Under humid climate conditions, rocks in lagoon were compacted and cemented, and carbonaceous mudstone deposited at the top of the sequence, forming an exposed cemented-carbonization zone. Under the alternating conditions of arid and humid climates, rocks in lagoon were subjected to multiple stages of weathering and leaching, forming dense cemented breccia. This configuration usually developed in low system tract, forming stable interlayers. (5) Low-energy environment+weak diagenesis. The original physical properties of the rocks were poor with high lime mud, and the subsequent diagenesis had not significantly improved the physical properties, and lithological interlayers were usually formed. Under the control of multi-stage sequences, the Mishrif Formation had continuously been changing the combination of sedimentation and diagenesis. The physical interlayers, mainly distributed in high-quality reservoirs, were thin, and small in scale and unstable. The lithological interlayers were associated with poor reservoirs. Lithological interlayers developed in different environments had different continuity. The tight cement zones were stable and the formation was divided into different development layer series of development. |
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| Keywords: | carbonate rock interlayers the Mishrif Formation sequence sedimentation diagenesis |
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