胡清富,刘春来,牟少敏,等. 伊拉克东巴油田Tanuma组泥页岩高效防塌钻井液技术[J]. 石油钻探技术,2022, 50(4):76-82. DOI: 10.11911/syztjs.2022081
引用本文: 胡清富,刘春来,牟少敏,等. 伊拉克东巴油田Tanuma组泥页岩高效防塌钻井液技术[J]. 石油钻探技术,2022, 50(4):76-82. DOI: 10.11911/syztjs.2022081
HU Qingfu, LIU Chunlai, MU Shaomin, et al. High-efficiency anti-sloughing drilling fluid technology for Tanuma shale of East Baghdad Oilfield in Iraq [J]. Petroleum Drilling Techniques,2022, 50(4):76-82. DOI: 10.11911/syztjs.2022081
Citation: HU Qingfu, LIU Chunlai, MU Shaomin, et al. High-efficiency anti-sloughing drilling fluid technology for Tanuma shale of East Baghdad Oilfield in Iraq [J]. Petroleum Drilling Techniques,2022, 50(4):76-82. DOI: 10.11911/syztjs.2022081

伊拉克东巴油田Tanuma组泥页岩高效防塌钻井液技术

High-Efficiency Anti-Sloughing Drilling Fluid Technology for Tanuma Shale of East Baghdad Oilfield in Iraq

  • 摘要: 伊拉克东巴油田South-2区块采用水平井开发Khasib组储层,但该区块首口以Khasib组为目的层的水平井在钻井过程中,因Tanuma组泥页岩多次发生坍塌卡钻,导致井眼报废。研究Tanuma组矿物组成、孔缝发育情况和水化膨胀特性发现,该组泥页岩具有黏土矿物含量高、水敏性较强、宏观层理发育明显、微观孔缝发育度高和水化膨胀速率快等特点,导致钻井过程中因黏土矿物快速水化膨胀而发生井眼失稳问题。基于此,通过室内试验,优选了封堵剂N-Seal及抑制剂U-HIB,对氯化钾聚磺钻井液的配方进行了优化,形成了高效防塌钻井液。室内试验发现,高效防塌钻井液具有良好的流变性、较强的封堵和抑制能力,能够满足Tanuma组泥页岩井段高效封堵的要求。该防塌钻井液在South-2区块3口水平井进行了现场试验,均成功钻穿Tanuma组泥页岩层段,顺利钻至设计井深,未出现坍塌掉块等井眼失稳问题。室内研究与现场试验结果表明,高效防塌钻井液能够有效解决Tanuma组泥页岩坍塌的技术难题,为实现Khasib组储层的有效开发提供技术支撑。

     

    Abstract: East Baghdad Oilfield in Iraq employs horizontal wells to develop reservoirs of the Khasib Formation in the South-2 block. However, in the drilling of the first horizontal well in the block with the Khasib Formation as the target, repeated sloughing and sticking happened drilling through the shale formation of Tanuma, which resulted in borehole abandonment. Researches on formation mineral composition, pore-fracture development, and hydration swelling characteristics show that the Tanuma shale features high clay mineral content, strong water sensitivity, evident macro bedding development, high micro pore and fracture development, and fast hydration swelling rate. As a result, wellbore instability occurs due to the rapid hydration swelling of clay minerals during drilling. Through laboratory evaluation, a high-efficiency anti-sloughing drilling fluid system was developed, by selecting N-Seal plugging agent and U-HIB inhibitor and optimizing the formula of the KCl/polysulfonate drilling fluid system. The evaluation demonstrated that the drilling fluid system with good rheologic characteristics presented strong plugging and inhibition performances, which met the requirements of high-efficiency plugging of Tanuma shale. In field tests of the drilling fluid in three horizontal wells of the South-2 block, Tanuma shale was drilled through without any wellbore instability issues. Laboratory evaluation and field tests show that the application of proposed drilling fluid system can effectively eliminate the technical difficulties of borehole instability in drilling through Tanuma shale, and provide support for the effective development of reservoirs in the Khasib Formation.

     

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