新型氮气泡沫压裂液体系研究及其在煤层气储层中的应用

Study on New Nitrogen Foam Fracturing Fluid System and its Application in Coalbed Methane Reservoir

针对沁水盆地某煤层气区块前期使用活性水压裂液体系压裂施工效果不理想等问题,通过室内实验研制了一种适合煤层气储层的新型氮气泡沫压裂液体系,具体配方为0.2%起泡剂SK-1+0.3%起泡剂SK-2+0.2%稳泡剂WP-11+2.0%防膨剂KCl+N_(2)。室内对该压裂液体系的综合性能进行了评价,结果表明:该压裂液体系在地层压力条件下能保持较长的泡沫半衰期,具有良好的起泡能力和泡沫稳定性;体系在40℃下剪切120 min后黏度仍能保持在90 mPa·s以上,具有良好的流变性能;此外,与常规氮气泡沫压裂液、活性水压裂液和胍胶压裂液体系相比,新型氮气泡沫压裂液体系具有更好的携砂能力、较低的滤失量以及较低的煤岩心渗透率损害率,能够适应煤层气储层压裂施工的需要。现场试验结果表明,与同区块内前期使用活性水压裂液的2口煤层气井相比,使用新型氮气泡沫压裂液体系施工的3口煤层气井见气时间明显缩短,日产气量明显提高,说明研制的新型氮气泡沫压裂液体系取得了较好的压裂施工效果。

In view of the poor fracturing effect of the active hydraulic fracturing fluid system in the early stage of a coal-bed methane block in Qinshui Basin,a new nitrogen foam fracturing fluid system suitable for coalbed methane reservoirs was developed through laboratory experiments.The specific formulation is 0.2%foaming agent SK-1+0.3%foaming agent SK-2+0.2%foam stabilizer WP-11+2.0%anti swelling agent KCl+N_(2).The comprehensive performance of the fracturing fluid system is evaluated indoors.The results show that the fracturing fluid system can maintain a longer foam half-life under the formation pressure,and has good foaming ability and foam stability.The viscosity of the system can still remain above 90 mPa·s after shearing at 40℃for 120 min,and has good rheological properties;In addition,compared with conventional nitrogen foam fracturing fluid,active hydraulic fracturing fluid and guanidine fracturing fluid system,the new nitrogen foam fracturing fluid system has better sand carrying capacity,lower filtration loss and lower coal core permeability damage rate,which can meet the needs of coalbed methane reservoir fracturing.The field test results show that compared with the 2 CBM wells with active hydraulic fracturing fluid used in the same block,the 3 coalbed methane wells constructed with the new nitrogen foam fracturing fluid system obviously shorten the gas production time and increase the daily gas production,indicating that the new nitrogen foam fracturing fluid system has achieved good fracturing effect.