东胜气田致密高含水气藏合采气井效果评价及产出影响因素分析

Production performance and controls on commingled-producing wells in tight reservoirs with rich water,Dongsheng gasfield

为了确定鄂尔多斯盆地北缘致密高含水气藏合采气井开发效果,指导同类型气藏合采气井高效开发。以东胜气田致密高含水气藏为研究对象,分析了单采井与合采井不同开发阶段、不同井区及纵向上的产出效果,以及合采井层间含气性差异对合采井产出的影响,明确了东胜气田致密高含水气藏合采井的开发效果及层间产出的影响因素。研究结果表明:①东胜气田致密高含水气藏合采井具有初期压力高、产量高的特征,但整体开发效果与气藏含气性或产水情况有相关性;②通过参数对比分析,合采井生产层产出效果与产层物性、含气性具有明显的正相关性,产层之间的含气性差异也会影响合采开发效果;③合采井稳定生产临界携液(携泡)流量与气井水气比也具有一定的相关性。结论认为:①东胜气田致密高含水气藏合采井初期压力、产量较高,但在低含气饱和度(高水气比)区域合采井整体开发效果较差,同时气田合采井随着开发时间的推移纵向上层间的产出状况也不断发生变化;②合采气井生产层物性、含气性越好,生产层的产出效果越好,且以物性条件为主导,但在较大的层间含气性差异下,合采井层间易发生严重的气液倒灌使得整体开发效果变差;③合采气井水气比越高,稳定生产临界携液(携泡)流量越大。

With rich water,some tight reservoirs in Dongsheng gasfield along the northern margin of Ordos Basin were studied to ascertain production performance in commingled-producing wells and further guide the highly efficient develop-ment.This performance was individuality analyzed for single and commingled wells at various development stages,in differ-ent well areas or in the vertical.And controls of gas-bearing property between layers on the performance were discussed for the commingled ones.Results show that(i)such commingled ones have characteristics of high initial pressure and pro-duction,but their overall performance is correlated with both gas-bearing property and water production in the tight reser-voirs;(ii)after parameter comparison,the performance in payzones has clearly positive correlation with physical properties and gas-bearing property,and the property difference between payzones also affects this performance;and(iii)the critical liquid-carrying(with foam)flow rate during stable production period is certainly related to water/gas ratio.It is concluded that,for the commingled-producing wells with relatively high initial pressure and production,their overall performance,however,is poor in somewhere with low gas saturation(high water/gas ratio).The interlayer production in the vertical is still evolving as the development time goes on.The better the physical properties and gas-bearing property are,the bet-ter the production performance is.The physical properties are dominant.Nevertheless,if there is large difference in the gas-bearing property between layers,gas and liquid are highly prone to severe backflow,resulting in not good overall per-formance.The higher the water/gas ratio is,the greater the critical liquid-carrying flow rate is.