硅酸盐钻井液LS的研制与性能评价

硅酸盐钻井液由于具有环保、价格低廉、抑制性能好等优点,近年来得到了人们的普遍关注.硅酸盐钻井液稳定井壁的机理为:当硅酸盐钻井液的pH值大于11时形成凝胶,而且硅酸盐还能与地层水中的高价金属离子形成沉淀,堵塞页岩的裂缝与孔隙,阻止了钻井滤液的侵入与压力的传递,同时由于硅酸盐与无机盐具有协同效应,增强了页岩的抑制性能,避免了井壁失稳的发生.研究了硅酸盐与无机盐KCl的加量、聚合物及pH值对钻井液性能的影响,得出了合理的钻井液配方:5%膨润土 5%硅酸钠 1%MV-CMC 2%SMP 3%KCl 0.5%其它添加剂.研究结果表明,所研制的硅酸盐钻井液LS具有很好的抑制性与抗温性能.

Study and property evaluation on silicate based drilling fluid LS

The silicate based drilling fluid caught people's attention in recent years again due to such characteristics as environmental acceptance, low cost, effective inhibition for shale swelling,. It is considered that the mechanism of borehole stability of silicate salts lies in forming gel when the pH value is over 11, and its depositing with metal ions in formation water environment. The gel and deposit shut off fracture and pore of the shale, stopping invasion of filtrate and reducing pressure transfer in formation. At the same time, the silicate salt has synergism effect with inorganic salt, strengthening inhibition for shale swelling and avoiding borehole failure. Effects of dose increase of silicate, KCl, polymer and pH value undulation on the drilling fluid rheological property were studied, then a reasonable formulation was proposed, which includes 5%clay,5%silicate,1%MV-CMC,2%SMP,3%KCl, and 0.5%additive. Test data verified excellent inhibition property and thermal stability of silicate based drilling fluid LS.