低损害钻井液体系的性能及在川西低渗气藏的应用

针对川西低渗气藏储层特性及损害机理,在重质碳酸钙类刚性颗粒表面接枝部分交联的聚合物制得储层保护剂SMRP-1,将其与井壁修补强化剂等复配制得低损害钻井液。室内评价了SMRP-1的阻渗性、酸溶性、与常见水基钻井液体系的配伍性,考察了低损害钻井液的各项性能,并在川西陆相低渗气藏储层江沙209HF井进行了现场应用。结果表明,SMRP-1的阻渗性能和酸溶性良好。SMRP-1对水基钻井液流变性的影响小,配伍性良好。低损害钻井液具有较好的阻渗、抗钙离子污染性能。含3%SMRP-1的钻井液形成的泥饼在15%盐酸中浸泡4 h的泥饼酸溶率为27%,酸溶性较好。低损害钻井液的储层保护效果较好,解堵作业后岩心的平均渗透率恢复值为89.59%。在现场应用中,低损害钻井液性能稳定,对储层的保护效果较好。低损害钻井液体系具有较强的井壁稳定和储层保护能力,对钻井液液相的渗透效应也具有良好的降低作用。

Performance of Drilling Fluid with Low Damage and Application on Low Permeability Gas Reservoir in Western Sichuan

Aiming at the reservoir characteristic and damage mechanism in low permeability gas reservoir of western Sichuan,a reservoir protective agent SMRP-1 was prepared by grafting partially crosslinked polymer onto the surface of rigid particle of heavy calcium carbonate.The low damage drilling fluid was prepared by compounding SMRP-1 with wellbore repairing and strengthening agent.The permeability resistance,acid solubility and compatibility between SMRP-1 and common water-based drilling fluid system were evaluated in laboratory,and the performance of low damage drilling fluid was investigated.The application of SMRP-1 in Jiangsha 209HF well of continental low permeability gas reservoir in western Sichuan Basin was carried out.The results showed that the permeability resistance and acid solubility of SMRP-1 were good.SMRP-1 had little effect on the rheology of water-based drilling fluid and had good compatibility.The low damage drilling fluid had good performance of resistance to permeability and calcium ion pollution.The acid solubility of filter cake formed by drilling fluid containing 3%SMRP-1 in 15%HCl for 4 hours was 27%,showing good acid solubility.The reservoir protection effect of low damage drilling fluid was good.The average permeability recovery value of core was 89.59%after blockage removal.In the field application,the low damage drilling fluid had stable performance and good reservoir protection effect.The low damage drilling fluid system had strong wellbore stability and reservoir protection ability,and had a good effect on reducing the penetration effect of liquid phase in drilling fluid.