Acta Petrolei Sinica ›› 2019, Vol. 40 ›› Issue (5): 594-603.DOI: 10.7623/syxb201905009

• Oil Field Development • Previous Articles     Next Articles

Microscopic mechanism of water sensitivity of pore-scale sandy conglomerate based on digital core

Li Junjian1, Cheng Baoyang1, Liu Renjing2, Meng Fanle1, Liu Yang1, Gao Yajun1, Ma Kang1, Jiang Hanqiao1   

  1. 1. State Key Laboratory of Petroleum Resources and Prospecting, Beijing 102249, China;
    2. Sinopec International Petroleum Exploration and Production Corporation, Beijing 100029, China
  • Received:2018-03-29 Revised:2018-08-13 Online:2019-05-25 Published:2019-06-03

基于数字岩心的孔隙尺度砂砾岩水敏微观机理

李俊键1, 成宝洋1, 刘仁静2, 孟凡乐1, 刘洋1, 高亚军1, 马康1, 姜汉桥1   

  1. 1. 油气资源与探测国家重点实验室 北京 102249;
    2. 中国石化集团国际石油勘探开发有限公司 北京 100029
  • 通讯作者: 李俊键,男,1983年2月生,2005年获中国石油大学(北京)学士学位,2010年获中国石油大学(北京)博士学位,现为中国石油大学(北京)副教授、博士生导师,主要从事提高采收率油藏工程方法方面的研究工作。Email:junjian@126.com
  • 作者简介:李俊键,男,1983年2月生,2005年获中国石油大学(北京)学士学位,2010年获中国石油大学(北京)博士学位,现为中国石油大学(北京)副教授、博士生导师,主要从事提高采收率油藏工程方法方面的研究工作。Email:junjian@126.com
  • 基金资助:

    国家科技重大专项(2017ZX05009-005)资助。

Abstract:

Xinjiang Mobei oilfield is a typical sandy conglomerate oil field. Field practice demonstrates that the reservoir faces serious water sensitive damage. To prevent the deterioration of reservoir properties after water sensitive damage, a study is conducted on the water sensitive damage mechanism of regional sandy conglomerate, and a method based on CT scanning experiment is proposed to investigate the mechanism of water sensitive damage by reconstructing 3D mineral distribution. By comparing the mineral distribution image determined by QEMSCAN with the gray-scale image of core slice scanned by Micro-CT, the corresponding relationship between the gray value of CT scanning and different mineral components is established. Then the whole core mineral components of the CT scanning are identified, and the identification results are verified through the X-ray diffraction analysis of mineral content. Through a comparison of the reconstructed 3D digital cores prior and posterior to water sensitivity, this paper analyzes the water sensitive damage mechanism. On this basis, this study simulates process of the two phases flow in porous media based on the intrusion-percolation theory, so as to obtain the variation characteristics of the relative permeability curves prior and posterior to damage. The results show that the main cause of water sensitive damage is the expansion, dispersion and migration of amorphous minerals (clay). In this process, the big pore-throats are divided into small pore-throats, and the damage to the throats is greater than that to the pores, thus leading to a decline in permeability. It can be known that after the occurrence of water sensitivity, not only the absolute permeability is decreased, but also the relative permeability is decreased by analysing the relative permeability curves. The water sensitivity is about 1.6-2.0 times the absolute permeability damage to the total effective permeability of oil-water two phases.

Key words: water-sensitive, CT in-situ scanning, QEMSCAN, pore scale, core refactoring, uneven damage, effective permeability

摘要:

新疆莫北油田是典型的砂砾岩油田,矿场实践表明油藏存在严重的水敏伤害问题。为防止水敏伤害后储层物性变差,针对该地区砂砾岩水敏损伤机理展开研究,提出了一种基于CT扫描实验进行三维矿物分布重构研究水敏损伤机理的方法。通过对比QEMSCAN确定的矿物分布图和Micro-CT扫描岩心切片的灰度图,建立CT扫描灰度值与不同矿物组分的对应关系。然后对CT扫描的整块岩心矿物组分进行识别,并利用X射线衍射分析的矿物含量对识别结果进行验证。通过对比水敏前后重构的三维数字岩心,对水敏损伤机理进行了分析,利用重构的数字岩心并基于侵入-逾渗理论模拟了两相渗流过程,获得了伤害前后相渗曲线的变化特征。结果表明,造成水敏损伤的主要原因是非晶体矿物(黏土)的膨胀、分散和运移,在这一过程中大孔喉被分割成小孔喉,且喉道的损伤程度大于孔隙的损伤程度,进而导致了渗透率的下降。通过相渗曲线分析可知,发生水敏后,不仅绝对渗透率降低,相对渗透率亦降低,水敏对于油水两相的总有效渗透率的伤害是绝对渗透率伤害的1.6~2.0倍。

关键词: 水敏, CT原位扫描, QEMSCAN, 孔隙尺度, 岩心重构, 不均匀伤害, 有效渗透率

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