A high CO₂ carbonate gas field offshore Sarawak, Malaysia, is scheduled for development. Fines migration has been identified as a potential risk for a sustained and stable production for this field, triggering this investigation. The reservoir investigated (subdivided in S3, S2, S1 formation) has an average 8% clays, of which over 50% are migratory illites and 15% migratory kaolinite. This paper discusses the laboratory findings and factors contributing to fines migration for this reservoir. We conducted core flood tests to determine critical flow rates for the onset of fines migration of high CO₂ hydrocarbon gas and CO₂-saturated brine within the production gas zone. In addition, we measured total suspended solids during each incremental rate stage and performed scanning electron microscopy–energy-dispersive X-ray (SEM–EDX) analysis on the effluents collected. We also performed mineralogical analysis of formation rocks to determine clay types, amount, and morphology. Core floods performed with CO₂-saturated brine on S3 and S2 cores showed damage at a critical flow rate of 10 ml/min with permeability recovery of 65–75%. This shows that CO₂-saturated brine tends to mobilize the fines such as illite and kaolinite. Core floods performed with high CO₂ hydrocarbon gas showed permeability recovery of 93–96% at rates up to 10 ml/min. SEM analysis on effluents collected showed presence of silicate and carbonate particles with size of 5–50 μm. A combined salt dropout and fines mobilization core flood showed a higher degree of formation damage due to fines mobilization with 74% permeability recovery compared to baseline permeability compared to core floods with high CO₂ hydrocarbon gas. However, the formation damage due to fines mobilization for this experiment was reversible. Overall, the results indicate that a high potential for fines migration in this type of carbonate system exists for CO₂-saturated brine flow with significant less potential for dry CO₂ flow.

中文翻译：

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马来西亚近海高压高温碳酸盐岩气藏细粉迁移研究

计划开发马来西亚沙捞越近海的高CO ₂碳酸盐气田。细粉迁移已被确定为该油田持续稳定生产的潜在风险，从而引发了这一调查。所研究的储层（细分为S3，S2，S1地层）平均有8％的粘土，其中超过50％是迁移伊利石和15％是迁移高岭石。本文讨论了该实验室发现的结果以及造成该油藏细粉迁移的因素。我们进行了岩心驱替测试，以确定高CO ₂烃气和CO ₂细粒迁移开始的临界流量-采气区中的饱和盐水。此外，我们测量了每个增量速率阶段的总悬浮固体，并对收集的废水进行了扫描电子显微镜–能量色散X射线（SEM–EDX）分析。我们还对地层岩石进行了矿物学分析，以确定粘土的类型，数量和形态。在S3和S2岩心上用CO ₂饱和盐水进行的岩心驱替在临界流速10 ml / min时显示出破坏，渗透率恢复率为65–75％。这表明饱和CO _2的盐水趋于动员伊利石和高岭石等细粉。用高CO ₂进行岩心驱替碳氢化合物气体以高达10 ml / min的速度显示出93-96％的渗透率恢复率。收集到的废水的SEM分析显示，存在大小为5–50μm的硅酸盐和碳酸盐颗粒。与基线渗透率相比，与高CO ₂烃类岩心驱替相比，盐分脱落和细粉动员岩心驱替相结合表现出更高的地层损害程度，这是因为细粉动员具有74％的渗透率恢复能力。但是，该实验中由于细粉动员造成的地层破坏是可逆的。总体而言，结果表明，在这种类型的碳酸盐系统中，对于CO ₂饱和盐水流而言，存在细粒迁移的高可能性，而对于干式CO ₂流而言，则存在显着较小的潜力。