This study fully explored the impact of temperature on the membrane quality of oil-based mud (OBM) using static gravimetric measurements, membrane efficiency and entrance pressure tests. More than 30 shale samples were used to assess the membrane behavior of several OBMs under elevated temperatures. Results suggested that OBM acted as a semi-permeable membrane at low temperatures (25–55˚C) since ion flow out of OBM and into shale was restricted despite the existence of a large ionic concentration gradient, while water flowed freely out of shale and into OBM because of the existence of a chemical potential difference. For temperatures higher than 55˚C, relatively higher ion flux into shale and slightly lower water flow out of shale was observed. Excessive heat may have possibly destabilized or even destroyed the emulsifier's structure that serves as a mechanism through which OBM performs as a semi-permeable membrane. The instability of OBM's emulsifier was further confirmed through entrance pressure testing where an appreciable reduction in entrance pressure of OBM was measured at high temperatures.

中文翻译：

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高温下油基泥浆膜质量和入口压力评价

本研究通过静态重量测量、膜效率和入口压力测试充分探讨了温度对油基泥浆 (OBM) 膜质量的影响。使用 30 多个页岩样品来评估几种 OBM 在高温下的膜行为。结果表明，OBM 在低温（25-55˚C）下充当半透膜，因为尽管存在较大的离子浓度梯度，但离子流出 OBM 并进入页岩受到限制，而水自由流出页岩和由于存在化学势差，因此进入 OBM。对于高于 55˚C 的温度，观察到进入页岩的离子通量相对较高，而流出页岩的水流则略低。过热可能会破坏甚至破坏乳化剂' s 结构作为一种机制，通过该机制，OBM 作为半透膜发挥作用。通过入口压力测试进一步证实了 OBM 乳化剂的不稳定性，其中在高温下测量到 OBM 入口压力明显降低。