The flow phases of fractured gas well in a conventional reservoir usually cover a linear flow period and a radial flow period. The elliptical flow period is usually regarded as a transition phase and thus ignored. The tight gas is the most realistic unconventional gas in China. Tight gas reservoirs are featured with low permeability and strong stress sensitivity. The pressure transmits slowly and every flow period is fairly extended. The elliptical flow phase at a tight gas well keeps a quit long time, even lasts for a couple of years. Therefore, the elliptical flow stage can't be ignored. When it comes to well test analysis, the conventional model is usually hard to match the double log curve in the field. To describe the flow phases more accurately, a flow model in elliptical coordinates is built through conformal transformation. The stress sensitivity coefficient is utilized in the model to consider the stress- sensitivity of tight gas reservoirs. After perturbation transforming and variable separation, the controlling equation is transformed into the Mathieu equation. Then it can be solved with a corresponding method. It's found that the stress sensitivity makes a higher pseudo-BHP drop and an end of derivative curve up warp. This model can simulate the flow period of tight sand gas well more accurately, and is significant to well testing of tight gas reservoir.
CAI Zhenhua
,
LIAO Xinwei
,
SHANG Baobing
,
AN Lei
. Analytical Model in Elliptical Flow Period of Tight Sand Gas Well Considering Stress Sensitivity[J]. Science & Technology Review, 2014
, 32(31)
: 50
-54
.
DOI: 10.3981/j.issn.1000-7857.2014.31.006
[1] 廖新维, 沈平平. 现代试井分析[M]. 北京: 石油工程出版社, 2002. Liao Xinwei, Shen Pingping. Modern well testing analysis[M]. Beijing: Petroleum Industry Press, 2002.
[2] Amini S, Ilk D, Blasingame T A. Evaluation of the Elliptical Flow Period for Hydraulically- Fractured Wells in Tight Gas Sands—Theoretical Aspects and Practical Considerations[C]. SPE Hydraulic Fracturing Technology Conference, College Station, Texas, USA, January 29- 31, 2007.
[3] RileyMF.Finitconductivityfractureinellipticalcoordinates[D]. California: Stanford University, 1991.
[4] 蔡振华, 廖新维, 廖红梅, 等. 致密压裂气井裂缝动态评价新方法[J]. 科 学技术与工程, 2013, 13(19): 5605-5608. Cai Zhenhua, Liao Xinwei, Liao Hongmei, et al. The new fractureperformance evaluation method for tight gas fractured well[J]. Science Technology and Engineering, 2013, 13(19): 5605-5608.
[5] Cai Zhenhua, Liao Xinwei. Evaluation research on performance of permeability and fracture in sulige gas field by new method[J]. International Journal of Oil, Gas and Coal Technology, 2014, 7(4): 347- 362.
[6] 罗瑞兰, 朱华银, 万玉金, 等. 岩石应力敏感对苏里格气井产能的影响[J]. 天然气技术, 2008, 2(6): 19-22. Luo Ruilan, Zhu Huayin, Wan Yujin, et al. The effect of rock stress sensitivity on well deliverability in sulige gasfield[J]. Natural Gas Technology, 2008, 2(6): 19-22
[7] 肖文联, 李闽, 赵金洲, 等. 低渗致密砂岩渗透率应力敏感性试验研究[J]. 岩土力学, 2010, 31(3): 775-779. Xiao Wenlian, Li Min, Zhao Jinzhou, et al. Laboratory study of stress sensitivity to permeability in tight sandstone [J]. Rock and Soil Mechanics, 2010, 31(3): 775-779.
[8] Pedrosa J. Pressure Transient Response in Stress-Sensitive Formations[C]//SPE California Regional Meeting, Oakland, California, USA, April 2- 4, 1986.
[9] 宁正福, 廖新维, 高旺来, 等. 应力敏感裂缝性双区复合气藏压力动态 特征[J]. 大庆石油学院学报, 2004, 28(2): 34-36. Ning Zhengfu, Liao Xinwei, Gao Wanglai, et al. Pressure transient response in deep-seated geothermal stress-sensitive fissured composite gas reservoir[J]. Journal of Daqing Petroleum Institute, 2004, 28(2): 34- 36.
[10] Jones J. A laboratory study of the effects of confining pressure on fracture flow and storage capacity in carbonate rocks [J]. SPE Journal of Petroleum Technology, 1975, 27(1): 21-27.
[11] Nur A, Yilmaz O. Pore pressure fronts in fractured rock systems, department of geophysics[D]. Cacifornia: Stanford University, 1985.
[12] 廖新维, 冯积累. 超高压低渗气藏应力敏感试井模型研究[J]. 天然气 工业, 2005, 25(2): 41-44. Liao Xinwei, Feng Jilei. Well test model of stress- sensitive gas reservoirs with super-high pressure and low permeability [J]. Natural Gas Industry, 2005, 25(2): 41-44.
[13] 张善杰, 金建铭. 特殊函数计算手册[M]. 南京: 南京大学出版社, 2011. Zhang Shanjie, Jin Jianming. Computation of special functions[M]. Nanjing: Nangjing University Press, 2011.
[14] 张善杰, 沈耀春. 马丢函数的数值计算[J]. 电子学报, 1995, 23(9): 41- 46. Zhang Shanjie, Shen Yaochun. Numerical computation of mathieu functions[J]. Acta Electronic Sinica, 1995, 23(9): 41-46.
