Zhao Zhenhua, Chen Sinan, Zhou Fengshan, Wei Zhongjin
Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes (National Laboratory of Mineral Materials), School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China.
Gels. 2022 Oct 10;8(10):643. doi: 10.3390/gels8100643.
With the development of the oil industry and the increasingly complex drilling environment, the performance of drilling fluids has to be constantly improved. In order to solve the problem of bentonite dispersion and hydration in a saline medium, a drilling fluid additive with good performance and acceptable cost was sought. The effects of several water-soluble polymers, such as cellulose polymers, synthetic polymers and natural polymers, on the rheology and gel suspension stability of calcium-based bentonite were compared in this study. Among the examined polymers, the xanthan gum biopolymer (XC) was the least negatively affected in the saline medium used. However, its high price limits its industrial application in oil and gas drilling fluids. In this study, a salt-tolerant polymer, modified vegetable gum (MVG), was prepared by a cross-linking modification of a natural plant gum, which is abundant and cheap. Then, a salt-tolerant polymer mixture called SNV was prepared, composed of the salt-resistant natural polymer MVG and the biopolymer XC. The salt tolerance and slurry ability of SNV and common water-soluble polymers were evaluated and compared. We then selected the most suitable Herschel-Bulkley model to fit the rheological curve of the SNV-bentonite aqueous suspension system. SNV improved the rheological properties of the calcium-based bentonite slurry and the dispersion stability of bentonite. In an SNV concentration of 0.35%, the apparent viscosity (AV) of the base slurry increased from 2 mPa·s to 32 mPa·s, and the low shear reading value at 3 rpm increased from 0 dia to 5 dia. This could greatly improve the viscosity and cutting carrying capacity of the bentonite drilling fluid. The bentonite drilling fluid prepared with SNV could be directly slurried with brine and even seawater; this means that when drilling in ocean, coastal saline water and high-salinity-surface saline water areas, the slurry preparation cost and preparation time can be conveniently reduced.
随着石油工业的发展以及钻井环境日益复杂，钻井液的性能必须不断提高。为了解决盐水介质中膨润土的分散和水化问题，人们寻求一种性能良好且成本可接受的钻井液添加剂。本研究比较了几种水溶性聚合物，如纤维素聚合物、合成聚合物和天然聚合物，对钙基膨润土流变学和凝胶悬浮稳定性的影响。在所研究的聚合物中，黄原胶生物聚合物（XC）在所用盐水介质中受到的负面影响最小。然而，其高昂的价格限制了它在油气钻井液中的工业应用。在本研究中，通过对一种丰富且廉价的天然植物胶进行交联改性制备了一种耐盐聚合物，即改性植物胶（MVG）。然后，制备了一种由耐盐天然聚合物MVG和生物聚合物XC组成的耐盐聚合物混合物SNV。对SNV和常见水溶性聚合物的耐盐性和造浆能力进行了评估和比较。然后选择最合适的赫谢尔 - Bulkley模型来拟合SNV - 膨润土水悬浮体系的流变曲线。SNV改善了钙基膨润土泥浆的流变性能和膨润土的分散稳定性。在SNV浓度为0.35%时，基浆的表观粘度（AV）从2 mPa·s增加到32 mPa·s，3 rpm时的低剪切读数从0刻度增加到5刻度。这可以大大提高膨润土钻井液的粘度和携岩能力。用SNV制备的膨润土钻井液可以直接用盐水甚至海水配浆；这意味着在海洋、沿海盐水和高盐度地表盐水区域钻井时，可以方便地降低配浆成本和配浆时间。
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