Morenov Valentin, Leusheva Ekaterina, Liu Tianle
Department of Oil and Gas, Saint Petersburg Mining University, 199106 Saint Petersburg, Russia.
Faculty of Engineering, China University of Geosciences, Wuhan 430074, China.
Polymers (Basel). 2021 Dec 19;13(24):4457. doi: 10.3390/polym13244457.
Construction of oil and gas wells at offshore fields often involves high formation pressure and the presence of swellable clay rocks in the section. In addition, productivity preservation is also an important aspect. For this purpose, it is necessary to reduce the solids content of the drilling mud. The purpose of this work is to develop, improve, and study compositions of weighted drilling muds with low content of solids, on the basis of organic salts of alkali metals and polymers for the construction of wells prone to rock swelling and/or cavings, as well as drilling fluids for drilling-in the formation. In order to achieve the set goal the following is required: Analysis of existing drilling muds of higher density for drilling wells in unstable rock intervals and for drilling in the productive formation; analysis of experience in using drilling systems on the formic acid salts base and substantiation of requirements for flushing fluids during well construction; development and investigation of drilling mud compositions on the formate base; and the evaluation of inhibiting effect of systems containing organic salts, polymer reagents, and calcium carbonate on clay samples. The developed drilling mud is characterized by a high inhibiting ability that allows minimized mud-weighting by the natural solid phase. This reduces the volume of prepared mud and facilitates the regulation of its properties by reducing the dispersion of drilled cuttings; it eliminates problems related to hydration and the swelling of active clay rocks; and stabilizes unstable argillites prone to caving. The low solids content, low filtration rates, and inhibitory nature of the mud allows high stability of the rheological properties of the mud, and preserves oil and gas reservoir productivity under conditions of elevated formation pressure.
海上油田油气井的建设通常涉及高地层压力以及该井段中存在可膨胀黏土岩。此外，保持产能也是一个重要方面。为此，有必要降低钻井泥浆的固相含量。本工作的目的是研发、改进并研究基于碱金属有机盐和聚合物的低固相含量加重钻井泥浆的配方，用于易发生岩石膨胀和/或坍塌的井的建设，以及用于地层钻进的钻井液。为实现既定目标，需要进行以下工作：分析用于不稳定岩石层段钻井和生产层钻进的现有高密度钻井泥浆；分析使用甲酸盐基钻井系统的经验，并论证井建设过程中对冲洗液的要求；研发并研究甲酸盐基钻井泥浆配方；评估含有有机盐、聚合物试剂和碳酸钙的体系对黏土样品的抑制效果。所研发的钻井泥浆具有高抑制能力，可使天然固相的泥浆加重降至最低。这减少了配制泥浆的体积，并通过减少钻屑的分散来促进其性能调节；消除了与活性黏土岩水化和膨胀相关的问题；并稳定了易坍塌的不稳定泥质页岩。泥浆的低固相含量、低滤失率和抑制特性使其流变性能具有高稳定性，并在高地层压力条件下保持油气储层的产能。
