具有特殊结构的微泡沫钻井液技术综述

近来开发出一种新的钻井液工艺--具有独特结构的微泡沫基钻井液,用它在世界范围内几百口井中顺利完成了枯竭储层的钻进.该钻井液的主要特点是,密度低,微泡沫具有架桥作用,基液粘度特别高,所以在钻低压地层时能很好地控制滤失量.微泡沫钻井液主要由增粘生物聚合物、表面活性剂和滤失控制剂组成,基液具有很高的低剪切速率粘度,通过在混合漏斗中采取合适的操作,表面活性剂将体系中的空气包裹起来即产生了微泡沫,钻井液从钻头喷射出时由于压力的降低也可能产生微泡沫,所以使用微泡沫钻井液不需要井场添加注入气体用到的设备.微泡沫具有特殊的结构,不会聚结,可循环使用;在井眼条件下能聚集在一起,在孔隙中及微裂缝处形成架桥,减少钻井液的侵入.在现场应用中微泡沫钻井液表现出许多优良性能:微泡沫能起到架桥粒子的作用,在枯竭储层及低压地层的钻进顺利;对粘土和页岩有好的抑制性能;流变性能易于维护,具有优良的井眼清洁能力、岩屑悬浮能力和滤失控制能力;可以连续完成上部地层和储层钻进,减少技术套管的使用;对井下工具无不良影响,可以用于定向井和水平井,不影响电测;井眼规则;完井顺利而且固井质量好;对环境的污染极小.介绍了微泡沫钻井液的室内研究及其现场应用情况.

Aphron-base drilling fluid technology

Recently, a new drilling fluid technology based on aphors uniquely structured micro bubbles was developed. It has been successfully employed in hundreds of wells all of world to drill depleted reservoirs. The drilling fluid consists mainly of a viscosifier, a fluid loss control additive and a surfactant, with the base fluid having high viscosity at low shear rate. The micro bubbles are generated by the use of a chemical surfactant that traps the air presenting in the system through blending funnel, or they are generated at pressure drop created by the jets of the bits. This fluid does not require an external source of injection of air. Uniquely structured, the fluid is non coalescing and recirculatable. In the down hole, they accumulate and create bridging in the throats and the micro fractures tip to avoid loss of fluid into the formation. Fields using reveal many prominent properties as follows: the micro bubbles present in the fluid act as bridging material, since they pass through zones of very low pressure and depleted formation without any problems; it provides excellent inhibition values to the clays and shale; its rheological properties are simple to maintain, permitting drilling the well with excellent hole cleaning, cuttings carrying capacity and filtration control; it permits drilling the intermediate and production holes jointly, eliminating the use of casing strings; the electric logs run were not affected by the fluid; the hole is in good gage; well completion goes smoothly and quality of the cement jobs are improved; it provides a minimum environmental impact. Lab study and in placing applications were introduced in this paper.