井下节流气井的生产动态模拟新方法

为了防止天然气水合物的生成以及井底积液的产生,鄂尔多斯盆地苏里格气田很多气井在井底都安装了井下节流装置,此类气井的产气量和井底流压均随着生产时间的增长而逐渐下降,没有一个绝对稳定阶段,故如何利用数值模拟的方法来实现对安装井下节流装置气井的动态模拟,是当前亟待解决的问题。为此,从油藏流动模型和井下节流气嘴流动模型出发,以井底为求解节点,通过耦合处理,提出了定气嘴尺寸生产的新理念;建立了气藏渗流、井下节流装置嘴流的计算模型,推导了新的数值模拟源汇项方程,实现了气藏渗流与井下节流装置嘴流的相互耦合。实例计算结果表明:新的数值模拟方法能够更加准确地体现安装井下节流装置气井的生产动态特征,能有效地应用于产能预测和稳产期评价,同时也为类似气井的产能计算提供了技术支撑。

A new production behavior simulation method for gas wells equipped with a downhole throttling device

In the Sulige Gas Field, Ordos Basin, many gas wells are equipped with a downhole throttling device at the bottom holes toprevent the formation of gas hydrate and the accumulation of downhole liquid. And their production rate and bottomhole flowing pressuredecrease gradually with the progress of production without an absolute stable stage. At present, the urgent problem lies in the dynamicsimulation on gas wells equipped with a downhole throttling device by means of numerical simulation. In this paper, therefore, based onthe reservoir flowing model and downhole throttling choke flowing model, a new concept of gas well production with a constant chokesize was presented through coupling treatment with the bottom hole as the solution node. Then, the computation model of gas reservoirseepage and downhole throttling choke flow was built. And finally, the source-sink equation of the new numerical simulation was developed.As a result, gas reservoir seepage and downhole throttling choke flow were coupled with each other. It is shown from case computationresults that this novel numerical simulation method can describe more accurately the production behavior of gas wells equipped witha downhole throttling device and can perform productivity prediction and stable production evaluation effectively. And furthermore, itprovides a technical support for the productivity calculation of similar gas wells.