低渗底水气藏射开水层气水合采新方法

NEW TECHNIQUE OF GAS WATER RECOVERING TOGETHER FOR LOW PERMEABILITY AND BOTTOM WATER RESERVOIR BY PERFORATING WATER-BEARING FORMATION

底水锥进会导致气井产能急剧下降 ,因此底水气藏通常采用避射水层、限制生产压差的方法防止底水锥进。但对于低渗透底水气藏 ,其临界锥进产量很小 ,有时甚至低于单井经济极限产量 ,无法实现经济开采。文章针对此类气藏 ,提出了射开水层、气水合采的新方法 ,将储层气水两相渗流转换为井筒两相管流 ,降低了气井生产过程中的能量损失。数值模拟计算结果表明 ,对此类气藏有针对性的气水合采 ,不仅可以提高气藏的最终采收率 ,还可以延长气井的稳产期。该方法适用于对底水分布认识相对清楚、底水能量不是很大的底水气藏 ,也适用于层间水气藏 。

Bottom water coning will cause the productivity of gas wells decrease dramatically. The measures, such as not perforating the water-bearing formation, and suppressing the producing pressure differential, are usually taken for bottom water reservoirs to prevent bottom water coning. But for a low permeability and bottom water reservoir, its critical coning production is low, sometimes even lower than the production what is economically recoverable. Aiming to the reservoirs, the article suggests the new technique of gas water recovering together by perforating water-bearing formation, converting the gas and water two phases percolation of the reservoir into the gas and water two phases flow through the tubing, and decreasing the energy loss in the producing process. The results of numeral simulation indicate gas water recovering together specially to this kind of gas reservoirs can not only improve the ultimate recovery of the gas reservoir but also extend the stable rate period. The technique is suitable to the bottom water reservoir with clearly understood bottom water distribution and small bottom water energy, also suitable to the inter-zonal water gas reservoirs. Besides, its economic feasibility also depends on the expense of the surface water processing costs.