摘要
为了揭示川西致密砂岩气层保护技术实施的工程地质条件，研究了川西致密砂岩气藏的工程地质特点：（１）发育多套气层，砂层厚度和规模差异显著；（２）地层压力剖面为超高压异常，呈现多个压力系统；（３）储层由浅部的近常规渐变为致密、超致密类型，基块毛管压力急剧升高；（４）裂缝发育非均质，微裂缝提供了致密砂岩储层的主要渗透性；（５）粘土矿物类型丰富，储层表现为强烈的水敏和碱敏性；（６）储层渗透率对应力变化异常敏感。致密砂岩气藏的工程地质特点决定了其损害机理显著地不同于常规油气层，保护技术措施更应强调针对性。分析表明，应用水平井技术、气体类工作流体或屏蔽式暂堵技术对裂缝性致密砂岩气层保护较理想。
Formation
damage has been recognizes as one of the key factors limiting the efficiency of exploration and
development for natural gas in tight sandstones. A comprehensive research on the engineering
geological conditions of tight gas sandstone reservoirs in western Sichuan Basin revealed the
following characteristics: ①existence of multiple pay zones differing markedly in thickness and
areal extent; ②abnormally high formation pressure and multi-pressure systems; ③capillary
pressure increasing sharply with increased burial and decreased permeability of the
reservoirs; ④fractures occurring heterogeneously, with microfractures being the major
contributor of reservoir permeability; ⑤strong water and alkaline sensitivity related to abundant
clays, and ⑥reservoir permeability being very sensitive to variations in stress conditions.
Analyses indicate that horizontal wells, gas based working fluids, and temporary shielding
techniques are suitable for the protection of such tight gas sandstone reservoirs.
出处
《西南石油学院学报》
CSCD
1999年第1期1-5,共5页
Journal of Southwest Petroleum Institute
基金
"九五"国家重点科技攻关项目
关键词
致密砂岩
致密气
工程地质
气层
天然气勘探
tight sandstone
formation damage control
geological engineering
Sichuan basin
