有机层状硅酸盐改善油基钻井液沉降稳定性室内评价

Laboratory Evaluation of Organophilic Phyllosilicate for Improving Sag Stability of Oil-based Drilling Fluid

基于油基钻井液有机土有机改性剂阳离子受高温易分解脱附,引起钻井液性能变差、加重材料沉降等问题,利用六水合氯化镁和十六烷基三甲氧基硅烷等为原料,合成了一种适用于柴油基钻井液体系的有机土(有机层状硅酸盐),用于改善油基钻井液的沉降稳定性;通过傅里叶红外光谱、X-射线衍射以及室内钻井液沉降实验进行结构表征和沉降稳定性评价。结果表明:该有机硅酸盐材料具备2∶1层状硅酸盐结构和以Si—C共价键连接的不对称链状有机官能团结构,且300℃无明显热分解;相比于大庆油田常用油基钻井液,该有机层状硅酸盐提高了油基钻井液的动切力、动塑比和储能模量,明显改善了1.4~2.0 g·cm^(-3)密度范围、150℃以下老化温度油基钻井液的悬浮性能和沉降稳定性能。

Based on the fact that the organoclay organic modifier cation of oil-based drilling fluid is easy to decompose and desorption at high temperature,which leads to poor drilling fluid performance and sag of weight material,an organoclay(organophilic phyllosilicate)suitable for diesel-based drilling fluid system was synthesized by using magnesium chloride hexamethonium and cetyltrimethoxysilane as raw materials to improve the sag stability of oil-based drilling fluid.The structure was characterized and the properties were evaluated by Fourier infrared spectroscopy(FTIR),X-ray diffraction(XRD)and the settling stability test of drilling fluid.The results showed that the organosilicate material had a 2∶1 layered silicate structure and an asymmetric organic functional group structure connected by Si—C covalent bond,and there was no obvious thermal decomposition at 300℃.Compared with the commonly used oil-based drilling fluid in Daqing oilfield,the organophilic phyllosilicate improved the yield point,yield point to plastic viscosity ratio and storage modulus of the oil-based drilling fluid,and obviously improved the suspension property and sag stability of the oil-based drilling fluid with density range of 1.4~2.0 g·cm^(-3) and the aging temperature below 150℃.