玛湖区块易漏地层防漏堵漏技术

通过玛湖区块易漏地层的漏失量、地层孔隙度和裂缝发育以及漏失压力剖面，分析玛湖区块漏失特征和漏失机理，采用形貌分析和粒径匹配方法，筛选防漏堵漏材料，评价和优化区域防漏堵漏体系。研究发现，玛湖区块二、三开漏失量大且复杂时率高，其中八道湾组、白碱滩组、克拉玛依组和乌尔禾组等地层孔隙和裂缝发育，承压能力差，为漏失多发地层；针对现场使用的防漏堵漏材料，提出了新的形貌优化组合以及微米级、毫米级的粒径匹配原则；所构建的SDSZ防漏体系砂床滤失深度较现场体系降低50%左右，SDDL堵漏体系的承压封堵能力可达7 MPa以上，且堵漏剂土酸酸溶率达60%以上。现场应用效果显著，漏失易发井的防漏成功率高达75%，堵漏作业一次堵漏成功率可达80%。研究结果表明，该防漏堵漏体系，可有效解决玛湖油田易漏地层的井漏问题。 

Study and Application of Technology for Preventing and Controlling Mud Losses in Mahu Block

Mud losses were frequently encountered in Mahu block. By carefully study the volume of mud losses, formation porosity, development of formation fractures and leaking pressure profile in this area, the characteristics and mechanisms of mud losses were analyzed. Lost circulation prevention and control slurries for the specific formations were evaluated and optimized, and lost circulation materials were selected using morphology analysis and particle size matching method. It was found in study that the second and the third intervals of the wells drilled in the Mahu block have higher volume of mud losses and high frequency of downhole troubles. The Badaowan formation, Baijiantan formation, Klamay formation and Wuerhe formation penetrated by these two intervals are full of pores and fractures and have low pressure bearing capacity, making them vulnerable to mud losses. Using the lost circulation materials available at the rig site, a new mud loss prevention slurry SDSZ and a mud loss control slurry SDDL were formulated with sized millimeter and micron particles by matching the shape of the particles and the morphology of the loss zones. The mud loss prevention slurry SDSZ was tested on a sand-bed and the depth of filtration of the SDSZ was 50% lower than that of the lost circulation control slurry previously used. The mud loss control slurry SDDL can strengthen the loss zones by increasing their pressure bearing capacity to above 7 MPa. Percent acid solubility of SDDL was at least 60%. In field application, 75% potential mud losses were prevented from occurring, and the success rate of controlling mud losses on the first try was 80%. The mud loss prevention and control slurries developed, as the study has shown, are able to effectively solve the mud loss problem occurred in Mahu block.