启动压力梯度和应力敏感效应对低渗透气藏水平井产能的影响

doi:10.11743/ogg20070417

摘要/Abstract

摘要：

由于低渗透气藏具有低孔、低渗特征,导致其气水渗流特征较为复杂,传统意义上的经典渗流规律不再适用于低渗透气藏。大量实验研究和现场应用证实低渗透气藏中存在渗流的非线性和流态的多变性,流体渗流不仅需要克服启动压力梯度,同时气体渗流还要受制于应力敏感效应影响。由于水平井是开发低渗透气藏最有效的方法之一,目前低渗透气藏水平井产能研究大多局限于传统意义上的经典渗流理论,通常忽略了应力敏感效应和启动压力梯度作用。针对低渗透气藏渗流特征,引入变换方法建立了低渗透气藏水平井产能模型,模型考虑了应力敏感效应和启动压力梯度的影响。并以某低渗透气藏为例,研究了应力敏感效应和启动压力梯度对低渗透气藏水平井产能的影响。结果表明:1)启动压力梯度和压力敏感对水平气井产量影响分别呈线性下降关系和幂函数下降关系;2)压力敏感效应比启动压力梯度对水平气井产量影响更为强烈;3)启动压力梯度达到0.00025 MPa/m,水平气井产量将降低77%;当介质变形系数达到0.15 MPa^-1,水平气井将停产;4)建议低渗透气藏水平井产能预测时必须考虑启动压力梯度和应力敏感效应的影响。

关键词: 低渗透气藏, 启动压力梯度, 应力敏感, 水平井产能

Abstract:

Water/gas percolation in low-permeability gas reservoirs is rather complicate because of the reservoirs'low porosity and low permeability.As a result,the traditional percolation law is inapplicable to this kind of reservoirs.Laboratory research and field application testify the nonlinearity of percolation and multi-variability of fluidal in the low permeability gas reservoirs.The percolation of fluid will not only need to overcome start-up pressure gradient,but will also be enslaved to stress sensitivity.Horizontal well technique is an effective method in low permeability gas reservoirs development.However,prediction of productivity of horizontal well in low permeability gas reservoirs is mostly carried out within the framework of traditional percolation theory and therefore fails to take start-up pressure gradient and stress sensitivity into consideration.In an attempt to fix the flaw,the conformal transformation is introduced in the establishment of a productivity model for horizontal wells in low-permeability reservoirs and the effects of start-up pressure gradient and stress sensitivity is studied based on the real data from a low-permeability gas reservoir.Results indicate that productivity of horizontal wells in low-permeability gas reservoirs decreases with start-up pressure gradient and stress sensitivity at a linear and an exponential relationship respectively.The stress sensitivity has a stronger impact on the productivity compared with start-up pressure gradient.When start-up pressure gradient reaches 0.00025 MPa/m,the productivity will be reduced to 77%;while when rock elastic distortion coefficient exceeds 0.15 MPa^-1,the horizontal gas well will have to be shut down.It suggests that start-up pressure gradient and stress-sensitivity effect should be considered to correctly predict the productivity of horizontal gas well in low permeability reservoirs.

Key words: low-permeability gas reservoir, start-up pressure gradient, stress sensitivity, productivity of horizontal well

中图分类号:

TE33

郭肖,伍勇. 启动压力梯度和应力敏感效应对低渗透气藏水平井产能的影响[J]. 石油与天然气地质, 2007, 28(4): 539-543. doi: 10.11743/ogg20070417 Guo Xiao,Wu Yong. Influence of start-up pressure gradient and stress sensitivity on productivity of low-permeability gas reservoirs[J]. Oil & Gas Geology, 2007, 28(4): 539-543. doi: 10.11743/ogg20070417

参考文献

[1] 冯曦,钟孚勋,罗涛.低渗透致密储层气井试井模型研究[J].天然气工业,1998,18(1):56～59
[2] 冯文光.非达西低速渗流的研究现状与进展[J].石油勘探与开发,1986,13(4):76～80
[3] 贺伟,冯曦,钟孚勋.低渗储层特殊渗流机理和低渗透气井动态特征探讨[J].天然气工业,2002,22(增刊):91～94
[4] 刘建军,刘先贵.低渗透岩石非线性渗流规律研究[J].岩石力学与工程学报,2003,22(4):556～561
[5] 刘晓旭,胡勇,李宁,等.低渗砂岩气藏气体特殊渗流机理实验研究与分析[J].特种油气藏,2007,14(1):80～83
[6] 吴凡,孙黎娟,乔国安.气体渗流特征及启动压力规律的研究[J].天然气工业,2001,21(1):82～84
[7] 刘高波,刘荣和,冯文光.低渗透气藏非达西渗流研究[J].大庆石油地质与开发,2007,26(1):65～67
[8] 郑维师,刘易非.低渗砂岩气藏中压敏效应对产能的影响[J].天然气工业,2004,24(12):113～115
[9] 康毅力,张浩,陈一健.鄂尔多斯盆地大牛地气田致密砂岩气敏感性综合研究[J].天然气地球科学,2006,17(3):335～338
[10] 宋传真,郑荣臣.致密低渗气藏储层压力敏感性及其对单井产能的影响[J].大庆石油地质与开发,2006,25(6):47～49
[11] 郭肖,杜志敏.低渗透气藏耦合流动模拟[J].天然气工业,2005,25(2):113～115
[12] 罗瑞兰,程松林.油气储层渗透率应力敏感性与启动压力梯度的关系[J].西南石油学院学报,2005,27(3):20～22
[13] 郭肖,杜志敏,疏壮志.裂缝性有水气藏水平气井产能分析[J].天然气工业,2006,(09):100～102
[14] 韩文功,张建宁,王金绎.济阳坳陷隐蔽圈闭识别与精细描述[J].石油与天然气地质,2006,27(6):849～859
[15] 王文环.提高薄互层低渗透砂岩油气藏采收率的有效开发技术[J].石油与天然气地质,2006,27(5):660～667
[16] 王昔彬,刘传喜,郑荣臣.大牛地致密低渗透气藏启动压力梯度及应用[J].石油与天然气地质,2005,26(5):634～639
[17] 宋子齐,程国建,杨立雷,等.利用测井资料精细评价特低渗透储层的方法[J].石油实验地质,2006,28(6):595～599