超低密度水泥用早强稳定剂GQD的研究与应用

长庆油田属低压，低渗透油藏，用常规密度水泥浆固井会压漏地层，导致注水泥失败，针对低压易漏地层固存在的问题，体系稳定性差；漂珠与水泥的相容性较差，而且密度越小，相容性越差，同时导致水泥石的抗压强度迅速减小。研制出了漂珠超低密度水泥浆用早强稳定剂GQD，CQD主要由促凝材料WJ（高介碱金属）、提粘增稠材料AS（碱土金属的硫酸盐）、有机分散剂FP和催化材料SK（胺类有机物）组成，介绍了GQD的作用机理，对GQD在漂珠水泥，粉煤灰水泥及纯水泥体系中的作用进行了室内试验。结果表明，GQD不仅解决了漂珠水泥体系易上浮分层，稳定性差的问题，还提高了水泥石的低温早期抗压强度，在400多口井中推广应用，固井质量合格率为100%，优质率大于80%，较好地解决了低压易漏地层长封固段的水泥低返和固井质量问题。

Study and application of an early strength stabilizing agent for light weight cement

Low pressure and low permeability reservoirs exist in Changqing Oilfield, and cementing with the slurry of conventional density can cause lost circulation and eventually lead to the failure of cementing operation. In accordance with the technical difficulties of cementing in the lost circulation formation, the defaults of the lightweight cement slurry system (1. 2 g/cm3) containing of microsphere are investigated. Specifically, the system has poor stability, and the compatibility between the microsphere and cement is poor, i. e. , the lighter the weight, the worse the compatibility , and the compression strength of cement decreases rapidly. An early strength stabilizing agent GQD is developed, for using in the ultra-light microsphere cement slurry. It mainly consists of the accelerating material WJ (high valency alkali metal), the thickening and viscosity promoting material AS (sulfonate of alkaline earth metal), organic dispersant FP and catalyzing material SK (amine organics). The working mechanism of GQD is introduced. and laboratorytests on the effects of GQD in microsphere cement, slag cement and mud are carried out. Results show that GQD effectively solves the problem of float separating and poor stability of the microsphere cement slurry system, and further improves the early compression strength in low temperature. Field using in over 400 wells show that it is very effective in improving the cementing quality of long intervals in low pressured and lost circulation formation.