苏里格气田东二区气水分布及产水控制因素分析

Analysis of Gas-Water Distribution and Water Production Control Factors in the East 2nd Area of Sulige Gas Field

针对低孔、低渗的致密砂岩气藏高效持续开发急需解决的气水分布及产水控制因素问题,通过苏里格气田东二区气藏地质和生产动态资料的综合分析,得出以下主要认识:地质构造和生烃强度控制本区气水分布的宏观格局,高产气井绝大多数发育在近烃源岩的低洼部位或微幅构造上;储层物性参数对气水分布起着关键的控制作用,物性好的砂体毛细管阻力小,天然气更易于驱替储集条件好的砂岩储层中的地层水形成气层,研究区气层孔隙度介于7%~14%之间,渗透率为(0.50~2.00)×10^-3μm^2;泥岩隔层等因素造成气水分布的复杂化,随着下伏山1段泥岩隔层厚度的增大,对应区域盒8段日产气量减小,日产水量增加;致密砂岩气藏产能受开发方式的影响很大,在气藏合理配产过程中,需要考虑压敏及速敏效应的影响:投产时间越长、配产及生产压差越大,气井出水速率越快,出水量越大。采用水平井开发,可增加气井的泄流面积、减小生产压差、提高产能、降低水气比,可以实现延长无水或低水采气期,从而提高采收率。

Aiming at the gas and water distribution and control factors needed for the efficient and sustainable development of low-porosity and low-permeability tight sandstone gas reservoirs, a comprehensive analysis of gas reservoir geological and production dynamic data was conducted in the East 2 nd area of Sulige gas field. The results show that: 1) the geological structure and the intensity of hydrocarbon generation control the macro-pattern of gas-water distribution in this area, and the gas reservoirs are developed on the low-lying part or micro-structure near the source rocks;2) the physical parameters of reservoir play a key role in controlling the gas-water distribution;3) the sand bodies with good physical properties have less capillary resistance, and natural gas is more likely to displace the formation water in sandstone reservoirs to form gas layers. The porosity of the gas layers in the study area is between 7% and 14%, and the permeability is between 0.50×10^-3 and 2.00×10^-3 μm^2. The factors such as mudstone barriers complicate the gas-water distribution. The thickness increase of the mudstone barrier in the first Member of Shanxi Formation leads to the decrease of daily gas production but increase water production in the 8 th Member of Shihezi Formation in the corresponding area. It is concluded that the production capacity of tight sandstone gas reservoirs is greatly affected by the development method. The pressure sensitive and velocity sensitive effects should be considered for a reasonable production allocation of gas reservoirs: the longer the production time is, the greater the production pressure difference is, the faster the gas well water production rate, and the larger the water production volume. The horizontal well development can increase the drainage area of gas wells, and it can, in turn, reduce the production pressure difference and the water-gas ratio, increase productivity, and extend the water-free or low-water gas recovery period and recovery ratio.