【作者】 岳前升；

【导师】 马保国；

【作者基本信息】 武汉理工大学 ， 建筑材料与工程， 2009， 博士

【摘要】 水平井技术已经成为油气开采中的关键技术之,而有“钻井工程血液”之称的钻井液特别是水平井钻井液技术更是钻井液技术领域研究的热点和难点。相对于直井和常规定向井,水平井对钻井液的技术要求更为严格和苛刻,尤其表现在井眼净化能力、降摩阻、稳定井壁、防漏失和储层保护等方面。同时,随着世界各国包括我国环境保护意识日益增强,钻井液所带来的环境问题日益受到重视,尤其是在环境敏感地区,如海洋、湖泊和内河等,相应的环境法规和制约也越来越严格。因此,研究和开发环境友好的、符合水平井钻井作业要求的钻井液技术势在必行。论文依托中国海洋石油总公司科技攻关项目“水平井钻井液技术研究”和湖北省自然科学基金项目“泥页岩水化膨胀特性和防膨机理研究”,针对水平井钻井液中的关键技术,根据钻井水力学理论和钻井液流变学理论,开发出水平井钻井液关键处理剂,在此基础上构建出水平井钻井液体系,并对水平井钻井液流变性、润滑性、失水造壁性和抑制性等进行了研究与分析;运用生化耗氧量法和发光细菌法研究了水平井钻井液体系和其添加剂的生物可降解性和生物毒性;对利用生物酶降解钻井液技术以及影响酶降解效果的因素展开分析和研究;对生物酶降解钻井液机理进行了研究。通过研究取得以下主要技术成果:1.根据水平井井眼净化理论和钻井液流变学理论,研制出水平井钻井液关键处理剂;根据储层保护理论构建出无固相弱凝胶水平井钻井液体系;系统分析和研究了钻井液性能。（1）根据水溶性聚合物抗盐理论,开发出增稠效果优异而且耐盐的多糖类增粘剂VIS;（2）根据胶体化学理论,选择具有“浊点”效应的聚合醇作为水平井钻井液的防塌润滑剂。（3）根据储层保护理论,构建出无固相弱凝胶钻井液体系:配浆水+0.1%NaOH+0.2%Na₂CO₃+0.7%增稠剂VIS+2.0%降滤失剂DFD+3%聚合醇润滑剂JLX,用可溶性盐调节密度。（4）无固相水平井钻井液呈现出快速弱凝胶特性;流变性能独特,具有较高的动塑比和很高的低剪切速率粘度,其动塑比（YP/PV）可达到1.5,低剪切速率（0.3转/分）粘度达到了55000mPa.s;（5）温度对无固相弱凝胶钻井液流变性影响程度较小;钻井液具有优异的抗盐能力,矿化度对流变性能基本无影响;并具有较宽的pH适应能力,pH在6-12范围内性能稳定。（6）钻井液具有很强的抑制能力,润滑能力接近油基钻井液。2.利用生化耗氧量法和发光细菌法研究了无固相弱凝胶钻井液体系及其添加剂的生物可降解性和生物毒性。（1）利用生化耗氧量法研究了无固相弱凝胶钻井液体系及其添加剂的生物可降解性,结果表明,无固相弱凝胶钻井液体系和单一添加剂在海水中能够生物降解;淀粉类降滤失剂DFD生物降解速率最大,其次是增粘剂VIS,再次是润滑剂JLX。（2）利用发光细菌法研究了无固相弱凝胶钻井液体系和添加剂的生物毒性,结果表明,水平井钻井液体系可以达到排放标准,淀粉类降滤失剂DFD、增粘剂VIS和润滑剂JLX均为无毒级别。（3）生物降解性和生物毒性评价结果表明,无固相弱凝胶钻井液为环境友好型钻井液。3.研究了无固相弱凝胶钻井液的储层保护效果,分析了储层损害机理;对生物酶降解多糖类聚合物钻井液进行了试验;对生物酶降解效果影响因素进行了探讨;对生物酶和其它氧化剂降解聚合物进行了对比与分析;分析了生物酶保护储层的作用机理。（1）无固相弱凝胶钻井液的储层保护实验结果表明,聚合物堵塞是造成储层损害的主要原因。（2）研究了利用生物酶降解多糖类钻井液的可行性和方法。试验结果表明,生物酶是多糖类钻井液的高效破胶剂,具有加量小、活性高等优点,0.1%生物酶SWM-2破胶率可以达到98.4%,矿化度对SWM-2破胶效果基本无影响;较适宜的破胶条件为:pH在6-7,温度不超过90℃,作用时间不低于2h。（3）储层保护作用机理研究结果表明,无固相弱凝胶钻井液、生物酶破胶液与储层岩石具有良好的配伍性。更多还原

【Abstract】 The technique of horizontal well has become one of the key techniques of oil and gas production, while the drilling fluid called "blood of well drilling engineering", especially for horizontal well drilling is the focus and also the problem in the area of drilling fluid technology. Related to the vertical well and conventional directional well, horizontal well has strict and severe requirements for drilling fluid techniques, such as hole cleaning ability, reduction of friction drag, well-bore stability, leaking prevention and reservoir protection. At the same time, with the enhancement of environmental protection in the world, including China, the environmental problems caused by drilling fluid are emphasized day by day, especially in the area sensitive to environmental change, such as in sea, lakes and inner rivers. The corresponding laws and constrains on drilling fluids are more and more strict. Therefore, it is imperative to develop and research on drilling fluid technique which could meet the requirement of both environment protection and horizontal well drilling.On the basis of CNOOC technical development project " Technical Study on Drilling Fluid for Horizontal Well " and Natural Fund Project Sponsored by Hubei Province "Research on Hydration Expansion Characteristics of Shale and Mechanism of Expansion Prevention",in allusion to the key techniques used in drilling fluid of horizontal wells , the key treating agents for drilling fluid in horizontal wells were developed based on drilling hydraulic theory and theory of drilling fluid rheology. On the basis stated above, a drilling fluid system used for horizontal well is developed, and the rheological characteristics, lubricating properties, filtration and wall-cake-building characteristics, inhibition properties of drilling fluid for horizontal well were studied and analyzed. A method of biologic-chemical oxygen consumption and a method of luminescent biacteria are used to study the biologic degradation and biologic toxicity of the horizontal well drilling fluid and its additive. The technique of biologic enzyme degradating drilling fluid and factors influencing its degradation effect are analyzed and studied and analyzed. The mechanism of biologic enzyme degradating drilling fluid is studied.The follow technical achievements are obtained in the study:1. Based on theory of horizontal wellbore cleaning and theory of drilling fluid rheology, the key additives for drilling fluid in horizontal wells were developed, a solid-free and weak gel drilling fluid system was established based on throry of reservoir protection. the properties of drilling fluid are analyzed and studied ystematically.（1） Based on the theory of salt resistance of water soluble polymer, a polysaccharide thickness agent VIS with good thickening effect and salt resistance is developed.（2） According to the theory of collochemistry, it is proposed that polyalcohol JLX with "clout point’’ effect is used as a anti-collapse lubricant in drilling fluid for horizontal well（3） According to the theory of reservoir protection, a solid-free and weak gel drilling fluid system was estblished including: water+0.1%NaOH+0.2%Na₂CO₃+0.7%thickener VIS+2.0%fluid loss additive DFD+3%lubricant JLX, soluble salt is used to adjust its density.（4） The drilling fluid has unique rheological characteristic with higher yield point-plastic viscosity ratio（YP/PV） and higher low shear rate viscosity（LSRV）. Its YP/PV is as high as 1.5, its LSRV（0.3round/min） is 55000 mPa.s, the effect of temperature on rheology is less.（5） Drilling fluid has excellent salt resistance. There is no effect of salinity on rheological property. Its pH adaptability is wide, properties of drilling fluid are stable with the range of 6-12（pH）.（6） It has strong inhibition ability, its lubricity is equal to oil based drilling fluid almost.2. Methods of bio-chemical oxygen consumption and luminescent bacterial are used to study the biodegradation and biological toxicity of the drilling fluid system and its additives.（1） Method of bio-chemical oxygen consumption is used to evaluate the biodegradation of the solid free weak gel drilling fluid and its additives. The results show that the drilling fluid system and its additive are all biodegradable. The biodegrading rate of starch loss control agent DFD is the highest, next is the thickening additive VIS, the last is lubricant JLX.（2） Method of luminescent bacterial is used to analyze the toxicity of the solid free weak gel drilling fluid and its additives. The results show that the toxicity of drilling fluid system can meet criterion of discharge, the toxicity of its additives including thickener VIS, fluid loss additive DFD andlubricant JLX are toxicity-free.（3） The results of biological degradation and toxicity evaluation indicate that the solid free weak gel drilling fluid is environment friendly.3. The effect of reservoir protection of the solid-free weak gel drilling fluid is studied, the mechanism of formation damage is analyzed. The degradation of polysaccharide polymer by biological enzyme is tested; the factors influencing the effect of enzyme degradation are discussed; biological enzyme and other oxidizing agent degrading polymer are compared. The mechanism of formation protection of biological enzyme is analyzed.（1） The result of experiment on reservoir protection of solid-free and weak gel drilling fluid shows that blocking by polymer is the major cause of formation damage.（2） The feasibility and methods of using the biological enzyme degradating polysaccharide drilling fluid are studied. The study result indicates that biological enzyme is a high efficient gel breaker for polysaccharide drilling fluid with low dosage and high activity. Factors of influencing the gel break of enzyme are studied. The results show that 0.10% of enzyme SWM-2 has a gel break rate 98.4%; there is no influence of salinity on the gel breaking effect, a more proper gel breaking condition is: pH value is within 6-7;temperature is lower than 90℃; the reaction time is not less than 2h.（3） The study result of reservoir protection mechanism indicates that the solid-free weak gel drilling fluid and the biological enzyme gel breaker fluid have a good compatibility with reservoir rocks.更多还原