长宁气田水平段钻井参数强化必要性浅析

The necessity analysis of drilling parameter optimizing in the horizontal section of shale gas wells in Changning area

北美页岩气水平井普遍采用大钻压、大排量、高泵压而钻井速度显著提高,对比可知我国川南地区长宁区块钻井参数偏低,制约钻井提速。以工区参数强化试验井A井的水平段为研究对象,通过对比实钻工艺参数与设计强化钻井参数,开展钻井参数强化执行情况分析及计算,并进行钻井硬件适应性评价。结果表明,实钻中钻压与机械钻速总体呈正相关关系;泵输出功率与泵压、钻头水功率及占比、钻头压降及占比等关键水力破岩能量指标随排量同步增加;现场试验中钻井硬件暴露出本身规格型号不匹配、长期服役硬件老化以及相关易损配件质量未满足要求等问题。结论认为:实钻参数低于设计强化参数导致井底破岩能量不足,进而影响机械钻速不及预期,故强化钻井机械与水力参数是必要的;同时钻井硬件适应性不理想成为限制参数强化的关键因素,应相应进行改造升级,包括优选强力钻头与螺杆、采用非API大水眼钻具及采购高质量泥浆泵易损配件等。

By applying high-level WOB,flow rate and pump pressure,the average drilling speed of shale gas wells in USA becomes much more faster,which demonstrates that the drilling parameters in Changning area might be relatively low somehow by comparison,and thus severely restricts ROP enhancing.To focus on the horizontal section of the parameter-optimizing trial well located in concerned area,basing on making comparison between actual drilling parameters and designed optimized ones,this paper mainly discusses how the optimization plan have been proceeded through related calculations,and criticizes the compatibility of equipped drilling hardware on spot.The results show:WOB may be positively relevant with the changes of ROP during the drilling;the key hydraulic power factors concerning pump and bit would increase simultaneously as the flow rate does;some negative facts shall be exposed somehow which against this very trial.The conclusion might be:on one hand,unexpectedly,the actual drilling parameters might be quite weaker than designed optimized ones that in return limits the down hole energy and thus reduces the ROP further,which means optimizations would be necessary;on the other hand,the fact that part of the drilling hardware cannot be trustable under optimized-parameter working condition shall be one of the key drilling speed-limiting factors,and should be upgraded accordingly,like choosing strengthened bits and down-hole motors,none-standard drill pipes and high-quality pump accessories.