非常规油气藏开采中的工程科学问题及其发展趋势

Scientific engineering problems and development trends in unconventional oil and gas reservoirs

非常规油气藏具有岩石致密、孔隙度和渗透率极低、孔隙类型具有多尺度性、强非均质性以及储量丰度低等地质特征,通常采用水平井和大规模"超级"分段压裂的井工厂模式再造一个缝网发育的"人工油气藏"而实现集约化高效开发。本文从高效开发的角度阐述了非常规油气藏开发过程中的工程科学问题:(1)考虑应力场和储层孔隙类型多尺度的地质建模问题(初始建模和压后二次建模);(2)非常规油气藏的裂缝扩展数值模拟问题;(3)非常规油气藏的生产数值模拟及其大规模数值计算;(4)井工厂中水平井和压裂裂缝空间位置的优化设计方法。结合课题组(中国石油大学油气渗流中心)的研究特色。综述了这些工程科学问题的发展现状和趋势,提出了基于非常规油气藏地质模型和数值模拟的井工厂开发模式工程参数的优化设计方法,对非常规油气藏的科学高效开发具有重要的意义。

Compared with conventional resources, unconventional oil and gas reservoirs mainly have the following geological characteristics: ultra-tight rocks with a relatively low porosity and ultra-low permeability, multiscale pore spaces, high heterogeneity, low abundance of reserves, etc. In order to achieve the intensive and efficient development of unconventional reservoirs, horizontal-drilling and massive hydraulic-fracturing technologies are usually applied to create an 'artificial oil and gas reservoir' with interconnected multiscale fracture networks. From the perspective of efficient development, this paper elaborates four engineering scientific problems in the development of unconventional reservoirs:(1) the problem of geological modeling(including initial modeling and secondary modeling after compaction) considering stress fields and multiscale pore spaces;(2) the problem of numerical simulation of fracture propagation in unconventional reservoirs;(3) the problem of production numerical simulation of unconventional reservoirs and the massive numerical computation that is involved;(4) optimization design of the positions of horizontal wells and hydraulic fractures in the 'well factory' development pattern. Considering the research features of the Center of Multiphase Flow in Porous Media(CMFPM) of China University of Petroleum(East China), this paper states the background and development trends of the above four problems, and puts forward the optimization design method for engineering parameters of the 'well factory' development pattern based on geological modeling and numerical simulation of unconventional reservoirs. This may be of great significance to the scientific and efficient development of unconventional reservoirs.