我国油田浅层气特征及其对钻井的影响

Features of shallow gas in Chinese oilfield and its impact on drilling

胡小强 2

广州海洋地质调查局，广东 广州 510760 国土资源部海底矿产资源重点实验室，广东 广州 510760

Guangzhou Marine Geological Survey, Guangzhou 510760, China Key Laboratory of Marine Mineral Resources,
Ministry of Land and Resources, Guangzhou 510760, China

浅层气在我国东部、东北部油田分布广泛，埋深主要在1 500 m以内。浅层气给油田钻井带来了诸多影响，钻井过程中会引发井涌、气侵、井眼垮塌甚至井喷等复杂情况。文中首先研究了我国油田浅层气的分布特征、甲烷与碳同位素特征及浅层气藏识别特征，然后分析了浅层气引起井喷的原因，提出先通过钻井过程中的气测显示异常及测井曲线“快起快降”特征进行浅层气的识别，再设计合理井身结构、调配合适的钻井液以及完善工程作业流程（如减小起钻抽吸压力及杜绝长时间停泵等措施）来预防浅层气对钻井的危害。

Shallow gas is widely distributed in the east and northeast oilfields of China at the depth of less than 1,500 m. Shallow gas causes many problems for oil drilling, such as well kick, gas invasion, wellbore collapse and even blowout. This paper discusses the distribution of shallow gas, ethane and carbon isotope characteristics and identification features of shallow gas reservoir in domestic oilfields and analyzes reasons of blowout caused by shallow gas. We also points out that the harm of shallow gas to drilling can be prevented by identifying shallow gas through the features of gas logging abnormal in the process of drilling and logging curve of "fast speed variation", re-designing well structure, compounding a suitable drilling fluid and improving engineering processes(such as reducing suction pressure, eliminating long time pump stop).

10.6056/dkyqt201504025