塔河10区碳酸盐岩裂缝型储层承压堵漏技术

针对塔河油田10区奥陶系裂缝型储层裂隙发育、井漏多发的问题，设计了一种桥堵颗粒粒度级配方法，并通过酸溶性材料优选，研制了承压堵漏配方。粒度级配方法以裂缝尺寸为基础，采用漏失量为主要评价指标，借助曲面响应优化设计法确定了粒度级配。实验评价结果表明，采用该粒度级配混配的桥堵材料颗粒粒度分布曲线连续、跨度广，无论是封堵较大裂缝，还是封堵中等裂缝或小裂缝，都有充足的对应粒度的桥堵颗粒。以该粒度级配方法为基础，设计的3套针对不同裂缝宽度范围的承压堵漏体系，堵漏性能良好，承压大于8 MPa，3 mm裂缝漏失量低于200 mL，2 mm和1 mm裂缝漏失量低于50 mL。堵漏配方中堵漏材料酸溶率高，在99%以上，形成的封堵层酸溶率可达98.4%。 

Study on Mud Loss Control under Pressure in Drilling Fractured Carbonate Reservoirs in Block Tahe 10

A mud loss control fluid was formulated to control mud loss under pressure during drilling the fractured Ordovician reservoirs in the Block Tahe 10, where mud losses prevailed in the past drilling operations. This mud loss control fluid was formulated with optimized sized acid soluble materials. In determining the sizing of the particles of the lost circulation materials (LCM), the amount of mud losses was used as the main evaluation index based on the sizes of the fractures found in the formations of the reservoir, and the response surface methodology (RSM) was used for optimized design of the sizing of the particles. Laboratory evaluation results showed that the particle size distribution has a continuous and wide-spanned distribution curve. Fractures of any sizes can be plugged with enough particles of matching sizes. Three mud loss control (under pressure) fluids for different sizes of fractures were formulated using the particle sizing technique. These fluids performed very well in controlling mud losses and pressure bearing capacity was greater than 8 MPa. The volume of mud loss through 3 mm fractures was less than 200 mL, and the volume of mud loss through 2 mm and 1 mm fractures was less than 50 mL. More than 99% of the LCM was dissolved by acids, while 98.4% of the particles in the layers of LCM formed on the surfaces of the borehole wall can be acid dissolved.