解除低渗砂岩气层钻井液伤害的洗井液研究与应用

Flushing Fluid Eliminating Damage to Low Permeability Sandstone Gas Reservoir by Drilling Fluid

钻井液对低渗砂岩气藏的伤害主要来自钻井液滤液,滤液产生的伤害主要为水锁,同时也有水敏膨胀及高分子聚合物在孔隙内壁的吸附滞留作用以及少量的固相微粒进入形成堵塞,导致产量降低。针对这一问题,主要从改变储层表面性质着手,研制出了洗井液NDF-1。该洗井液使低渗砂岩气藏由强亲水变为弱亲水,消除储层毛细管压力,溶解进入的部分固相,拆散堵塞,从而提高气驱水效率。室内实验表明,洗井液NDF-1可以使现场DIF伤害后岩心渗透率恢复率得到明显提高,平均恢复率提高率达到133.45%。在CB3-3井进行了现场试验,通过试气结果表明,单井产量提高率达到35.71%。

Filtrates of drilling fluid cause damage to low permeability sandstone gas reservoir, usually by water block, and sometimes by plugging by solid particles, retention of adsorbed polymer on the surface of pore throats, and water sensitive formation clays, all resulting in reduced rate of production. A flushing fluid, NDF-1, was developed to solve these problems. NDF-1 reversed the surface of the reservoir rocks from strong hydrophilicity to weak hydrophilicity, thus minimized the effect of capillary force and entered into the interior of some solid particles to disintegrate and remove solid blockades. Laboratory study showed that NDF-1 remarkably recovered permeability of rocks impaired by DIF damage, with percent recovery of permeability by 133.45%. Well CB3-3, treated by NDF-1, had gas production rate increased by 35.71% during well test.