适用于深水水基钻井液的温敏聚合物流型调节剂

针对深水水基钻井液低温流变调控的要求，利用温敏聚合物在对温度响应的过程中有显著的流体力学体积和分子构象变化的性质，以N-异丙基丙烯酰胺（NIPAM）和丙烯酰胺（AM）为单体，合成了一种流型调节剂PNAAM。通过傅里叶红外光谱（FT-IR）表征了产物的官能团。热重分析显示产物初始热分解温度在300℃。浊度分析显示，单体配比和盐浓度均是通过影响分子链中亲水基团与水分子氢键的强度来影响产物的LCST（低临界溶解温度）。PNAAM在钻井液中4、25和65℃流变参数比值为AV_4℃∶AV_25℃∶AV_65℃=1.75∶1.22∶1、PV_4℃∶PV_25℃∶PV_65℃=1.8∶1.4∶1、YP_4℃∶YP_25℃∶YP_65℃=1.8∶1∶1.09。机理分析认为，温度小于LCST时，分子链中亲水基酰胺基团做主导，PNAAM分子溶于水，无可测量的流体力学半径；温度大于LCST时，分子链中疏水基做主导，PNAAM分子链之间疏水缔合作用增强，形成三维网状结构，黏度增大，聚合物粒度增大，泥饼膨润土颗粒更加致密有序。 

A Temperature Sensitive Polymer Flow Pattern Modifier for Water Base Drilling Fluids for Deep Water Drilling

A flow pattern modifier PNAAM was developed to satisfy the needs of rheology control of water base drilling fluids at low temperatures in deep water drilling. PNAAM was synthesized with N-isopropyl acrylamide (NIPAM) and acrylamide monomers based on the fact that temperature sensitive polymers, when responding to the changes of temperature, show remarkable changes in their hydrodynamic volumes and molecular conformation. In laboratory study, the functional groups of the product of the synthesis reaction were characterized using FT-IR, and thermogravimetric analysis showed that the initial thermal decomposition temperature of the synthesis product was 300 ℃. Turbidity analysis of the synthesis product showed that the molar ratio of the monomers and salt concentration affect the LCST of the synthesis product by affecting the strength of the hydrogen bonds between the hydrophilic groups in the molecules of the synthesis product and the water molecules. The ratios of rheological parameters of PNAAM at 4 ℃, 25 ℃ and 65 ℃ in drilling fluids were: AV_{4 ℃}∶AV_{25 ℃}∶AV_{65 ℃}= 1.75∶1.22∶1, PV_{4 ℃}∶PV_{25 ℃}∶PV_{65 ℃}= 1.8∶1.4∶1 and YP_{4 ℃}∶YP_{25 ℃}∶YP_{65 ℃}= 1.8∶1∶1.09. Analysis of the mechanisms shows that before the LCST is reached, the hydrophilic amide groups in the molecular chains of PNAAM are dominating the solution and PNAAM is soluble in water, hence there is no measurable hydrodynamic radius for PNAAM. When the environment temperature is greater than LCST, the hydrophobic groups in the molecular chains of PNAAM are dominating the solution and the hydrophobic associating action among the molecular chains of PNAAM is becoming stronger, thereby forming a 3-D network structure in the solution, which increases the viscosity of the solution and the particle sizes of the polymers, and makes the bentonite particles in the mud cakes more dense and more orderly arranged.