一种无固相储层保护钻井液体系研究

Study on a Solid-free Drilling Fluid System for Reservoir Protection

针对裂缝、低孔低渗储层钻进过程中,钻井液胶体堵塞裂缝和孔隙,导致胶体无法有效返排,影响后期油气田的产能恢复。采用接枝共聚法,以玉米淀粉为原料、苯乙烯磺酸钠(SS)、二烯丙基二甲基氯化铵(DMDAAC)和N-乙烯基吡咯烷酮(NVP)为接枝单体制备了一种抗温低黏度降滤失剂JL-HT,通过红外光谱、表面形貌对其结构进行分析,并与关键处理剂复配配制出无固相储层保护钻井液体系。结果表明,抗温基团、刚性基团可有效提高降滤失剂的热稳定性。通过降滤失剂的加量、抗氧化剂来控制无固相钻井液热稳定性,满足钻井需求。钻井液胶体在岩心中长时间静置,可有效热分解,解决了常规无固相钻井液漏失到裂缝性储层或堵塞孔隙而造成胶体返排困难的问题。

In the process of drilling in fractured,low-porosity and low-permeability reservoirs,drilling fluid colloids blocked cracks and pores,so that colloid could not flow back effectively,which affected the productivity recovery of oil and gas fields in the later stage.A temperature-resistant and low-viscosity fluid loss reducer JL-HT was prepared by graft copolymerization using corn starch as raw material,sodium styrene sulfonate(SS),diallyl dimethyl ammonium chloride(DMDAAC)and N-vinylpyrrolidone(NVP)as graft monomers.The structure was analyzed by infrared spectrum and surface morphology.And solid-free drilling fluid system for reservoir protection was prepared by mixing with key treatment agents.The results showed that the thermal stability of the fluid loss reducer was effectively improved by the anti-temperature group and the rigid group.The thermal stability of solid-free drilling fluid was controlled by adding fluid loss reducer and antioxidants to meet drilling requirements.The colloid of drilling fluid could be effectively thermally decomposed by standing in the core for a long time,which solved the problem of colloid flowback caused by conventional solid-free drilling fluid leakage into fractured reservoirs or plugging pores.