盐下高压特低渗透油田钻完井关键技术

Key technologies for drilling and completion in sub-salt carbonate reservoir with high pressure and low permeability

卞德智 董本京 孙振纯

BIAN De-zhi DONG Ben-jing SUN Zhen-chun

中国石油天然气勘探开发公司研究中心, 北京 100083 中国石油勘探与生产分公司, 北京 100011

肯基亚克盐下油藏是埋藏在3000 m厚的盐丘下的地质条件复杂、低孔特低渗、异常高压碳酸盐岩油藏。开发初期曾遇到的问题是地层结构复杂、巨厚的盐丘难以钻进、射孔完井产量低,钻井成本高,不具备经济开采的价值。在认真研究油藏地质特征、地层压力和工艺要求的基础上,通过简化井身结构,筛选适合于盐丘地层的钻井液体系,尝试裸眼完井方法等手段,有效地把直井的钻井周期从原来的500 d左右缩短到180 d左右,单井初始产量从原来的30多吨提高到平均200 t以上,多口井初始产量达到500 m3/d以上,有一口井初始日产量千吨以上。盐下钻井周期缩短和单井产量提高的因素很多,但是井身结构简化、突破巨厚盐丘的钻井技术和裸眼完井方法是其中最关键的技术。

The sub-salt carbonate reservoir in Kenhkiak,Kazakhstan is an oil pool with abnormal pressure,low permeability and complicated geological conditions.At the initial stage of development,problems encountered in drilling practice were the complex of casing program,thick salt dome difficult to drill and low production rate due to perforation completion.The drilling cost was about 10 million USD.Based on careful study about the geological features of the reservoir,pore pressure and drilling technical requirements,the casing program was simplified from 4-string design to 3-string design,anti-salt drilling fluid system like twitterion polymer system was screened out to use on field and open hole completion was tested.As a result,the drilling duration of vertical wells were reduced from initial over 500 days to 180 days or so.The daily production rate of a single well increased from the original 30 tons to over 200 tons in average.So far,many wells have been into production with initial daily output over 500 m3/d.The shortening of drilling duration and the increase of initial production rate of a single well can be attributed to many factors.However,the simplification of casing program,break-though of salt dome drilling and open completion are undoubtedly the key factors.

10.3969/j.issn.1000-7393.2006.06.004