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钻衰竭油藏涉及到许多技术和经济问题 ,常使得进一步开发老油田无利可图。大多数问题集中在不能控制漏失和压差卡钻。尽管较便宜的钻井液有可能伤害地层 ,但通常在特殊层段仍使用较便宜的钻井液 ,因为使用这些钻井液可以抵消昂贵的泥浆漏入地层造成的损失。如果作业者选择欠平衡钻井 ,那么在一些应用中为了安全作业所需的额外时间和设备就会严重降低项目的经济性。已经开发出一种钻进易漏地层时控制漏失的特殊钻井液 ,这种钻井液由特定的表面活性剂和聚合物组成 ,可以形成一种微泡体系或Aphrons体系 ,这些微泡或Aphrons包裹在一种独特的增黏体系中。设计的微泡钻井液通过控制衰竭、高渗砂岩地层的漏失同时稳定压实页岩或其他地层以帮助建井。微泡体系吸引人的特征之一是它不需要空气或泡沫钻井中使用的额外设备 ,也不需要增加成本和涉及安全的压缩机、高压水龙带以及连接装置 ,该钻井液体系使用常规的钻井液混合设备就可获得抗压性能好、可变形的微泡。介绍了在北海衰竭油气藏中控制井下泥浆漏失的特殊微泡钻井液体系的开发与应用。项目的关键问题是在上部产层由于采用超过平衡钻压 (>50 0 0lb/in2 )带来昂贵的泥浆漏失和裸眼射孔的风险 ,需要在钻进过程中采取临时封隔措施。该井采用微泡体系没有发生井
Drilling depleted reservoirs involves many technical and economic issues, often making it unprofitable to further develop old fields. Most problems are focused on losing control and sticking pressure. Although cheaper drilling fluids may harm the formation, cheaper drilling fluids are often used on special intervals because the use of these fluids counteracts the loss of expensive mud leaking into the formation. If operators choose to underbalance drilling, the extra time and equipment required for safe operation in some applications can severely reduce the economics of the project. A special drilling fluid has been developed to control leaks when drilling into a draining formation that consists of specific surfactants and polymers that form a microbubble system or Aphrons system that encapsulates In a unique tackifying system. The designed microbubble drilling fluid helps stabilize shale or other formations by controlling depletion and failure of hypertonic sandstone formations. One of the attractive features of the microbubble system is that it does not require additional equipment used in air or foam drilling and does not require cost and safety related compressors, high pressure hose and connections, which use conventional drilling Liquid mixing equipment can get good compression performance, deformable microbubbles. The development and application of a special microbubble drilling fluid system for controlling the loss of downhole mud in depleted North Sea reservoirs are introduced. The key issue for the project is the risk of expensive mud loss and open hole perforation in the upper production due to the use of overrun WOB (> 50 0 lb / in2), requiring temporary containment during drilling. Well did not happen well using microbubble system