多层合采气藏井底压力响应模型通解

General solution of bottomhole pressure response models in commingling production of stratified gas reservoirs

为了提高单井产能和降低生产成本,许多生产井都是按多层合采方式进行生产的。多层气藏的开采规律有别于常规气藏,研究其井底压力变化规律对开发此类气藏具有重要的意义。为此,在分析研究多层气藏渗流机理的基础上,建立了以单井为研究对象的多层气藏渗流数学模型;然后通过拉氏变换对该数学模型进行求解,获得多层合采气井拉氏空间井底压力动态响应数学模型;通过Stephest数值反演技术获得真实空间下的井底压力响应解,通过编制计算机程序,获得了井底压力动态响应曲线,从而分析了响应特征及其影响因素,进而研究了分层流量剖面的变化规律。该研究成果对合理、高效开发多层气藏具有指导意义。

To reduce the production cost and increase a single well's productivity,the commingling production is usually adopted for many gas wells.The exploitation rules for commingling production for stratified gas reservoirs are different from those for regular gas reservoirs.Thus,it is of great significance to study the changing patterns of the bottomhole pressure of wells in the stratified gas reservoirs.Therefore,based on an analysis of the flow mechanism of a stratified reservoir,a seepage flow mathematical model was first established with a single well taken as a study object.Then,the solutions for this model were obtained by using Laplace transformation,with which a dynamic response model was also built for the bottomhole pressure in the Laplace space.By Stehfest numerical inversion,the bottomhole pressure in the real space was obtained and the dynamic response curve is drawn by using a computer program.Moreover,the characteristics of the response and the factors influencing the response were analyzed.Based on the above,the changing patterns of the stratified flow profile were investigated.The study results are important in guiding the reasonable and effective commingling production of the stratified gas reservoirs.