【作者】 张广垠；

【导师】 夏柏如；

【作者基本信息】 中国地质大学（北京） ， 钻井工程， 2014， 博士

【摘要】 加蓬G区块位于非洲中西部国家加蓬的东北部，是中石化海外战略勘探开发投资的重点油气区块之一，大多施工井为探井，地质条件复杂、裂缝发育，在钻井施工过程中遇到了许多有关井筒稳定和储层保护的技术难题，如井壁垮塌、缩径、井漏、气侵等井筒失稳问题突出，不仅严重影响了井下安全和钻井效率，而且还影响了勘探开发进度和整体经济效益。通过对加蓬G区块已钻井地质、工程、测井、录井、固井，以及测试资料进行分析研究，对该区域的储层岩性特征、地质特征等有了深刻认识，明确了加蓬G区块存在的井筒稳定与储层保护方面的技术难点和问题。井筒稳定方面主要包括钻井过程中因井筒失稳导致的井壁坍塌、井眼缩径、井漏、井涌，以及由此引起的固井质量差等钻井技术难点与问题。全面分析了加蓬Ｇ区块井筒稳定机理，找出井筒失稳导致井下复杂事故的各种因素和主要原因，提出了保持井筒稳定的技术对策；优选了加蓬G区块保持井筒稳定的钻井液体系和配方；应用粒度分析技术开展屏蔽封堵稳定井壁技术研究，形成了应对加蓬Ｇ区块复杂地层井筒稳定的“屏蔽封堵保持井筒稳定技术”，建立了该区块保持井筒稳定的一套系统理论和方法，形成了一套预防和处理井漏的钻井技术方案和防气窜防漏失水泥浆体系，并在G-9井、G-10井进行了现场技术应用研究，收到很好的效果，避免了钻井过程中井筒失稳现象的再次发生，保障了井筒稳定；解决了加蓬Ｇ区块钻井过程中井筒失稳问题，保障了井下安全与固井质量，提高了钻井施工速度，加快了加蓬G区块开发的进程。全面分析了加蓬Ｇ区块储层保护问题，通过孔隙度、渗透率测试、全岩分析X衍射实验，以及液相与固相颗粒侵入实验、岩心的敏感性实验、水锁损害实验等；开展了加蓬G区块储层伤害因素及损害机理分析研究，找出储层污染的各种因素和主要原因，提出了保护加蓬G区块储层的主要技术措施，优选了钻井液、完井液体系和配方，确定了加蓬G区块储层保护的钻井液体系与推荐配方，形成了一套适合加蓬Ｇ区块钻井配套技术和储层保护技术，经G-11井现场应用表明，效果明显，解决了加蓬Ｇ区块钻井过程中储层污染问题，为加蓬Ｇ区块的高效开发提供了技术支撑；提出在加蓬G区块推荐采用全过程欠平衡钻井技术与控压钻井技术保护储层。更多还原

【Abstract】 The G Block in Gabon is located northeast of the Port Gentil of the Ogooue province. Itis an important exploration and development block of Sinopec Overseas. Most of the drilledwells are exploratory wells. For the complex geological conditions, many technical problemsrelated to wellbore stability and reservoir protection were encountered during the drillingprocess, such as well leakage, collapse, severe gas invasion and other wellbore instabilityproblems not only seriously affected the efficiency of drilling and downhole safety, but alsoseriously affected the progress and overall exploration and development effectiveness.From the drilling geology, engineering, wireline logging, mud logging, cementing, welltest data analysis and study, the reservoir lithology, geological features have been known.There exist wellbore stability and reservoir protection aspects of technical difficulties andproblems. Wellbore instability caused by the collapse, lost circulation, kicks, and the resultingpoor cementing quality etc.Comprehensive analysis of wellbore stability mechanism of G block was done toidentify the main factors for wellbore instability. The main reasons for the wellbore instabilitywere found and some technical countermeasures were proposed. Drilling fluid system andadtives are preferable."Shield blocking technique to maintain wellbore stability" is carriedout by particle size analysis and formed to deal with G block complex formation wellborestability. A set of theory and methods to maintain the wellbore stability has been formed andconducted in well G-9, G-10, received very good results, avoided the emergence of wellboreinstability, safeguarded the wellbore stability during drilling; Form a well leakage preventionand treatment programs and protect the downhole safety and cementing quality. Acceleratethe speed of drilling and the development process of G block.Comprehensive analysis of the reservoir protection of G block through porosity,permeability testing, X-ray diffraction experiments, as well as core-sensitive experiments,carried out in G block and damage mechanism of reservoir, to find the main reasons for thepollution of G block reservoir, proposed the main technical measures to protect G blockreservoir, drilling fluid system is preferable, well G-11application shows that the effect isobvious. The whole process of using underbalanced and managed pressure drillingtechnology to protect the reservoir was suggested.更多还原