煤田地质与勘探2017，Vol.45Issue(1)：152-157,6.DOI:10.3969/j.issn.1001-1986.2017.01.029
气体吸附对煤层安全钻井液密度的影响
The influence of gas adsorption on the density of drilling fluid
陈德飞 1孟祥娟 1康毅力 2彭永洪 1周玉 1秦汉1
作者信息
- 1. 中国石油塔里木油田分公司油气工程研究院,新疆库尔勒 841000
- 2. 西南石油大学油气藏地质及开发工程国家重点实验室,四川成都 610500
- 折叠
摘要
Abstract
Cleat is extremely developed in coal seam, which leads to strong heterogeneity. During drilling in coal seam, borehole wall is easy to collapse and bury drilling tool.It is of great importance to prepare reasonable drilling fluid for keeping the stability of borehole wall. At present, the classical continuum theoretic model maily is used to forecast the density window of safe drilling fluid, resulting in poor actual effect in site. As a matter of fact, there are not only developed cleats in coal seam, but also a large amount of CH4 occuring as adsorbed gas, weakening the mechanical strength of coal and making the borehole wall more unstable. Thus in view of the particularity of coal seam as a non-continuum medium, the authors used the discrete element model constructed on the basis of the continuum mechanics to analyze the borehole stability of coal seam in the process of drilling, and determined the best anti-collapse drilling fluid in combination of the analysis method of continuum medium strenghth and in consideration of the influence of gas adsorption on the weakening of the mechanical strenghth of coal and rock.Finally the case calculation using the above theory was conducted according to the coal seam data and in-site drilling fluid data from Ningwu basin in Shanxi province. Results showed that the density of anti-collapse drilling fluid must be greater than 1.009 g/cm3and plugging agent needs to be added in drilling fluid to improve its sealing capacity.关键词
煤层/非连续介质/气体吸附/钻井液密度/井壁稳定Key words
coal seam/non-continuum medium/gas adsorption/drilling fluid density/stability of borehole wall分类
能源科技引用本文复制引用
陈德飞,孟祥娟,康毅力,彭永洪,周玉,秦汉..气体吸附对煤层安全钻井液密度的影响[J].煤田地质与勘探,2017,45(1):152-157,6.
