黏弹性表面活性剂的研制及其在微泡钻井液中的应用

以氨基化合物、长链酰氯等为原料，研制出微泡钻井液用阴离子型黏弹性表面活性剂VES-1。通过优选胶束促进剂、助表面活性剂等优化出VES-1黏弹性体系。该体系黏弹性好，泡沫稳定性强，0.01 r/min低剪切黏度可达100 000mPa·s，泡沫半衰期可达18 min以上。在VES-1黏弹性体系基础上，结合文23地层特点，通过优选稳泡剂、降滤失剂等形成高触变性微泡钻井液体系，并对其性能进行了评价。评价结果表明:VES-1微泡钻井液体系具有高触变性，能够快速形成结构，10 s初切可达到12 Pa以上，而且初、终切相差不大，有利于悬浮携带岩屑，可对低压易漏地层形成快速有效封堵；120℃下注入325 mL钻井液承压即可达到10 MPa以上，可解决低压易漏地层钻进过程中地层漏失难题；VES-1微泡体系同时具有良好的抗压缩性，30 MPa下密度最高升高不超过0.05 g/cm3，该体系经120℃老化16 h后性能稳定，密度无变化，可抗10%复合盐水污染；同时具有良好的润滑抑制性，润滑系数比普通聚合物体系低54%以上，各项性能能够满足文23储气库建设的需要。 

A Viscoelastic Surfactants: Its Development and Application in Micro Foam Drilling Fluids

A viscoelastic anionic surfactant VES-1 has been synthesized with amino-compound and long-chain acryl chloride for use in micro foam drilling fluids. A micro foam mud treated with VES-1 was formulated with selected micelle enhancer and secondary surfactants. The micro foam mud had good viscoelasticity and stable foam. Low shear rate (0.01 r/min) viscosity of the foam mud is 100 000 mPa·s, and the half-life longer than 18 min. Based on the formation characteristics of the Wen-23 gas storage, the VES-1 micro foam mud was further treated with foam stabilizer and filter loss reducers to form a micro foam mud of high thixotropy. Laboratory evaluation results have proved its high thixotropy and ability to quickly form network structure inside the mud. The initial (10 s) gel strength of the VES-1 foam mud was at least 12 Pa, and there was only slight difference between the 10 s and 10 min gel strengths. This is especially beneficial to carrying drilled cuttings out of hole and plugging low pressure thief zones to avoid mud losses. VES-1 is apparently superior to the commonly used surfactants (such as OP-10) in mud loss control under pressure. In mud loss experiment, injection of 325 mL of the VES-1 mud at 120℃ increased the pressure to above 10 MPa, indicating that this mud can help resolve mud loss problem in low pressure formations. VES-1 micro foam mud also had good pressure resistance; its density increase did not exceed 0.05 g/cm3 under 30 MPa. After aging at 120℃ for 16 h, the mud properties remained unchanged. The VES-1 mud is able to resist contamination by 10% compound saltwater. It also has good lubricity; the friction coefficient of the VES-1 mud is 54% less than commonly used polymer drilling fluids. Properties of the VES-1 micro foam mud are able to satisfy the needs for the construction of the Wen-23 gas storage.