川东三高气井固井水泥浆设计应注意的问题以及现场应用效果

CEMENTING SLURRY DESIGN FOR HT/HP AND HIGH H_2S CONTENT GAS WELLS

川东高含硫气层具有高温、高压、压力窗口窄、高低压共存、气水同层、裂缝发育等特点,固井水泥浆设计难度大。固井期间经常又漏又喷,层内、层间窜通,水泥浆返高不够,导致固井后期出现窜槽、微间隙,形成长期窜流通道;同时高温、高压、高含硫使水泥石和套管受到腐蚀,影响水泥环的完整性及正常钻井和开发,给实施增产措施带来难以补救的困难。针对高温、高压、高含硫天然气井固井设计水泥浆时应注意的问题,对水泥性能、监控混灰、复核实验等进行了合理设计,包括平衡压力设计、材料选择、干混监控、组织协调等以及吸取××井水泥浆设计的教训,为类似的固井作业水泥浆设计提供了有效的借鉴。

HT/HP and high H2S content gas wells,similar with one in eastern Sichuan Basin,are featured by narrow pressure window,coexistence of high and low pressure,gas/water in same layer and developed fractures.So it's difficult to design cementing slurry.During cementing some problems such as lost circulation and blowout,in-layer and interlayer crossflow,lower cement top may happen usually,resulting in channeling,micro-gap,and crossflow path in later cementing.Moreover,cement stone and casing are corroded by HT/HP and high H2S content.It can bring negative effects on the integrity of cement sheath,drilling development and stimulation.Aiming at problems of cementing slurry designed for such kind of gas wells,this study designs the property of cement,solid chemical,fluid and compound monitoring,rechecking experiment etc.,including balanced-pressure design,chemicals selection,and organization coordination.Some design experiences from one well have been summarized.It can provide guidance for new design.