A discontinuous medium mechanical model for the sidewall stability prediction of coal beds

被引：0

作者：

Chen, Mian ^{[1
]}

Zhao, Haifeng ^{[1
]}

Jin, Yan ^{[1
]}

Ding, Yunhong ^{[2
]}

Wang, Yonghui ^{[2
]}

机构：

[1] School of Petroleum Engineering, China University of Petroleum

[2] Langfang Branch, PetroChina Research Institute of Exploration and Development

来源：

Shiyou Xuebao/Acta Petrolei Sinica | 2013年 / 34卷 / 01期

关键词：

Coal bed; Collapse pressure; Elementary model; Sidewall stability; Size effect;

D O I：

10.7623/syxb201301018

中图分类号：

学科分类号：

摘要：

Coal beds are discontinuous media with well-developed cleats and fractures. The prediction of safe-density window of drilling fluid with the continuous medium mechanical model currently used can not achieve good effects in coal beds, and the sidewall destabilization is one of the difficulties in coalbed methane drilling. For this reason, we established a divergent elementary model for coalbed collapse pressure based on the discontinuous medium mechanical theory, and a discontinuous coalbed mathematical equation for collapse pressure and breakdown pressure was deduced via ground stress, interval and dip angle of cleat, size of wellbore, cohesive force and friction angle of face cleat. Moreover, sidewall stabilization coefficients related to wellbore liquid-column pressure and collapse pressure in the equation were defined. The analysis indicated that sidewall stabilization can be reinforced by increasing liquid-column pressure when the sidewall stabilization coefficient is positive, otherwise, both the liquid-column pressure and the formation pressurization capacity should be enhanced in order to keep sidewall stabilized. The size effect analysis showed that collapse location is sensitive to the size of wellbores, however, collapse pressure changes a little with various sizes of wellbores.

引用

页码：145 / 150

页数：5

共 14 条

[1]

Luo D., Chu W., Wu X., Et al., Analysis on economic benefits of coalbed methane drilling technologies, Petroleum Exploration and Development, 36, 3, pp. 403-407, (2009)

[2]

Shen R., Qu P., Yang H., Advancement and development of coal bed wellbore stability technology, Petroleum Drilling Techniques, 38, 3, pp. 1-7, (2010)

[3]

Gao D., Xian B., Research on design models of multi-lateral well structure for coal-bed methane, Acta Petrolei Sinica, 28, 6, pp. 113-117, (2007)

[4]

Yang L., Sun M., Hu A., Et al., New technology series favorable to develop coal bed methane reservoirs, Acta Petrolei Sinica, 23, 4, pp. 46-50, (2002)

[5]

Liang D., Pu X., Xu X., Particularity of coal collapse and drilling fluid countermeasure, Journal of Southwest Petroleum Institute, 24, 6, pp. 28-31, (2002)

[6]

Qu P., Shen R., Yang H., Et al., Evaluation model of wellbore stability in coal seam, Acta Petrolei Sinica, 30, 3, pp. 455-459, (2009)

[7]

Shen H., Cheng Y., Zhao Y., Et al., Research on in-situ stresses and borehole stability of coal seam in Jingbian gas field, Rock and Soil Mechanics, 30, S2, pp. 123-126, (2009)

[8]

Chi W., Main geological factors affecting coalbed methane recoverability of no. 1 syncline, Coal Geology & Exploration, 27, 1, pp. 29-32, (1999)

[9]

Du H., Zhang S., Xu D., Et al., Study on anti-sloughing, degradable and temporary plugging drilling fluid in CBM multi-laterals horizontal well, China Coalbed Methane, 7, 1, pp. 30-33, (2010)

[10]

Zhang Z., Tang C., Li L., Et al., Numerical investigation on stability of wellbore during coal bed gas mining process, China Mining Magazine, 15, 9, pp. 55-58, (2006)

← 1 2 →