抗高温耐盐增黏剂及其无固相钻井液体系研究

Study on High Temperature Salt-resistant Viscosifier and the Formulated Solids-free Drilling Fluid

选用2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酰胺(AM)、单体X为主要单体,合成出钻井液用抗高温耐盐增黏剂BDV-200S。研究了BDV-200S的分子结构、分子量及其分布、耐热性能,通过高温流变性能测试、高温老化黏度保留率性能测试、高温老化浆体悬浮重晶石实验和井底动态循环模拟实验等测试方法,表征了增黏剂BDV-200S的抗温性能及热稳定性能,并考察了120℃、150℃、180℃等不同温度下其与同类产品在无固相钻井液中的应用性能。结果表明,BDV-200S为目标聚合物;重均分子量近200万且分布集中;抗温能力良好,180℃高温老化16 h后黏度保留率大于45%,且浆体颜色仍呈乳白色,无大量重晶石沉淀,高温悬浮能力较好;经过180℃井下4个循环周模拟实验后黏度保留率大于50%;抗盐性能较好,随着盐含量增加至饱和,增黏剂在盐水中的黏度保留率保持为25%;在中高温及高温无固相钻井液体系中应用良好,经180℃老化后黏切性能保持率较高,常温中压滤失量为5.0 m L,150℃高温高压滤失量为19 m L,性能优于国内外同类产品。

A high temperature salt-resistant viscosifier, BDV-200 S, has been developed from 2-Acrylamido-2-methylpropane sulfonic acid（AMPS）, acryl amide（AM） and another monomer X. Studies have been conducted on the molecular structures, molecular weights and distributions, and the thermal stability of BDV-200 S molecules. Rheology and functioning stability at elevated temperatures were studied through high temperature rheological measurement, ratio of viscosity retention after aging at high temperature, suspension of barite in the aged muds treated with BDV-200 S, and bottom-hole dynamic circulation simulation test etc. The performances of BDV-200 S in solid-free drilling fluids at 120 ℃, 150 ℃, and 180 ℃ were compared with those of the similar products. These studies reveal that the BDV-200 S synthesized is the product designed. BDV-200 S has a weight average molecular weight of about 2,000,000 which is distributed in a narrow range. After aging at 180 ℃for 16 h, the BDV-200 S solution still retained viscosity of greater than 45% of its original viscosity, and the color of the solution was still white. No barite settlement has been found of the solution, meaning that the suspending capacity of BDV-200 S is satisfactory. A laboratory test simulating mud circulation in hole with bottom hole temperature of 180 ℃ indicated that the solution, after 4 cycles of circulation, still retained viscosity more than 50% of its original viscosity. In salt resistant performance testing, the viscosity of the saltwater increased with the concentration of BDV-200 S in a linear relationship. Drilling fluids treated with BDV-200 S has API filter loss of 5.0 mL, and HTHP filter loss of 19 mL at 150 ℃. The evaluation reveals that BDV-200 S possesses a better performance than other similar products.