水驱多层砂岩气藏射孔层位优化的实用方法

OPTIMIZATION METHOD OF PERFORATED INTERVALS FOR WATER DRIVE GAS RESERVOIRS WITH MULTIPLE SAND BEDS

水驱多层气藏采用多层合采方式进行开采 ,是减少开发井网、井数 ,提高单井产量 ,防止气井出砂 ,从而实现气田高效开发的有效途径。但若层间互不连通 ,由于各气层气水边界及驱动能量不尽相同 ,在多层合采时 ,边水推进速度不一致 ,某单层的提前见水将导致全井产量和压力大幅度下降 ,甚至可能导致气井关闭。因此 ,此类气田一般采用射孔层段优化来保证射孔单元内各气藏 (层 )的边水能够均匀推进 ,使气井具有较高的产量和较长的稳产时间 ,从而提高气田采收率。文章利用物质平衡原理推导出此类气田射孔层位优化的一种实用方法 ,通过优化气层在平面上的射孔井网、井数和纵向上的打开程度 ,使同一射孔单元内各层保持相同或相近的采气速度 ,可达到射孔层位优化的目的。该方法在青海涩北气田得到应用 ,提高了气田单井产量 ,并对气田稳产和提高采收率有积极意义。

Recovering water drive gas reservoirs with multiple beds by multiple-zone production is an effective way to decrease production well network and number, increase single well production, prevent sand production of gas wells and realize efficient development of gas fields. But if there are no channels between the beds, the edge water advancing speed is different when multiple-zone production is conducted since the difference of the gas-water boundary and drive energy of each bed. Some single bed will have water breakthrough in advance, which causes the well production and pressure dropping greatly, even shutting-up the gas well. So, the optimization method of perforated intervals is usually used for this kind of gas fields to make the edge water advancing homogeneously in the different beds of the perforated unit, to make the gas well higher production and longer stable production period, and to improve the recovery factor of the gas field. Applying the material balance principle, the article develops a practical method for optimization of perforated intervals of gas fields. With optimizing the perforation well network and number and the longitudinal penetration of gas beds, the same or similar gas recovering rate can be obtained for the different beds in the same perforated unit, and the target of perforated intervals optimization can be achieved. The method has been applied in Sebei gas field of Qinghai province and the production of single well has been increased. Also, the method is helpful for stable production and recovery improvement of the gas field.