Ahmed Ashraf, Basfar Salem, Elkatatny Salaheldin, Gajbhiye Rahul
College of Petroleum Engineering and Geosciences, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
ACS Omega. 2020 Dec 11;5(50):32689-32696. doi: 10.1021/acsomega.0c05068. eCollection 2020 Dec 22.
Drilling fluids have a crucial continued role in drilling a successful well; however, most of the drilling technical and operational challenges are incorporated with the drilling mud stability and properties. The solid particles settling in drilling mud that deteriorates its stability is a common issue encountered in high-pressure high-temperature (HPHT) conditions. This issue, known as solids sagging, may eventually result in stuck pipes, wellbore instability, and loss of circulation. The objective of this work is to introduce garamite to enhance the stability of hematite-based invert emulsion mud under HPHT situations. The used garamite and hematite weighting material were analyzed using X-ray fluorescence, scanning electron microscopy, and particle size distribution to identify their compositions, morphologies, and particle sizes. The effects of adding different concentrations of garamite (0.5, 1.0, 1.25, and 1.5 g) to the field formula of hematite-based invert emulsion mud were investigated. The mud density, stability, sagging tendency, rheology, viscoelasticity, and filtration properties were studied to formulate a stabilized and distinguished-performance drilling mud. The obtained results indicated that garamite did not change the mud density while enhancing the emulsion stability by increasing the electrical stability proportionally with the added garamite quantity. The sagging experiments showed that adding 1.25 g of garamite is sufficient to prevent the sagging problem in both static and dynamic conditions as it was enough to enforce the sag parameters into the safe range of sag performance indicators. This 1.25 g of garamite improved the yield point by 152% from 19 to 48 lb./100 ft with a slight increase in plastic viscosity from 14 cP for base mud to 18 cP and significant increase in the gelling strength and viscoelastic properties. Adding 1.25 g of garamite showed a slight enhancement in the filtration properties as the filtrate volume was reduced by 8% from 3.7 to 3.4 cm and the filter cake thickness has 16% reduction from 2.69 to 2.26 mm. As a result, a mud with distinguished performance, in terms of rheology, suspension, sag performance, and stability, was obtained. Hence, a basis for safely drilling the HPHT formations was delivered, which reduces the drilling cost by minimizing the nonproductive time.
钻井液在成功钻井过程中起着至关重要的持续作用；然而，大多数钻井技术和操作挑战都与钻井泥浆的稳定性和性能有关。固体颗粒在钻井泥浆中沉降会降低其稳定性，这是在高压高温（HPHT）条件下常见的问题。这个问题，即固体下沉，最终可能导致卡钻、井眼不稳定和井漏。这项工作的目的是引入硅镁石以提高基于赤铁矿的反相乳化泥浆在HPHT情况下的稳定性。使用X射线荧光、扫描电子显微镜和粒度分布对所用的硅镁石和赤铁矿加重材料进行分析，以确定它们的成分、形态和粒度。研究了向基于赤铁矿的反相乳化泥浆现场配方中添加不同浓度硅镁石（0.5、1.0、1.25和1.5克）的效果。对泥浆密度、稳定性、下沉趋势、流变学、粘弹性和过滤性能进行了研究，以配制出稳定且性能优异的钻井泥浆。所得结果表明，硅镁石不会改变泥浆密度，同时通过与添加的硅镁石量成比例地提高电稳定性来增强乳液稳定性。下沉实验表明，添加1.25克硅镁石足以在静态和动态条件下防止下沉问题，因为它足以将下沉参数强制纳入下沉性能指标的安全范围内。这1.25克硅镁石使屈服点从19磅/100英尺提高了152%至48磅/100英尺，塑性粘度从基础泥浆的14厘泊略有增加至18厘泊，凝胶强度和粘弹性性能显著增加。添加1.25克硅镁石使过滤性能略有增强，滤液体积从3.7立方厘米减少了8%至3.4立方厘米，滤饼厚度从2.69毫米减少了16%至2.26毫米。结果，获得了一种在流变学、悬浮性、下沉性能和稳定性方面性能优异的泥浆。因此，为安全钻进HPHT地层奠定了基础，通过最大限度地减少非生产时间降低了钻井成本。
