油井水泥膨胀、降失水双效材料的研究

A Fluid-Loss Controllable Expansive Material for Oilwell Cement

油井水泥固有的高体积收缩和高失水特性是造成油气井气窜和固井质量差的主要原因，也是国内外固井界尚未很好解决的重要问题之一。本文研制了一种新型的油井水泥膨胀材料（ＤＤ 型） ，并对其在不同条件下的膨胀量、抗压强度、胶结强度和工程性能进行了评价。此外，还对该材料的作用机理进行了理论分析。结果表明：当其掺量为水泥的１０ ％ ～２０ ％ 时，不仅可使油井水泥浆产生足够的塑性膨胀和后期膨胀，而且还能有效地控制水泥浆的失水量。掺入材料后，水泥浆的其它工程性能也满足ＡＰＩ规范和现场施工的技术要求。

One of the major problems for cementing operation at home and abroad is gas migration in cementing and poor bonding quality in sheath/formation and sheath/casing,which can be attributed to the higher shrinkage and the higher fluid-loss of oilwell slurry.A novel expansive material for oilwell cement was studied in this paper.The experimental findings indicated that the slurry with 10～20%(BWOC) DD expansive material showed not only significant expansion but also lower filtration.Other engineering properties of the slurry,such as thickening time,compressive strength and rheology,also satisfied API specification.Furthermore,the mechanism concerning both expansion and fluid-loss control was discussed theoretically.