本文關鍵詞： 頁巖氣藏 壓裂水平井 非穩(wěn)態(tài)滲流 遞減分析 產量預測　出處：《西南石油大學》2017年碩士論文　論文類型：學位論文

【摘要】：在當前國際能源供需矛盾日漸突出的情勢下,新能源的有效開采對國家戰(zhàn)略部署具有重要的意義,而頁巖氣作為一種新非常規(guī)能源,尤其是北美國家成功開發(fā)之后,備受世界各國的關注。論文以頁巖氣藏儲層特征及滲流規(guī)律為基礎,分析了頁巖基質表觀滲透率和裂縫滲透率的變化特征,建立了考慮頁巖基質中氣體多尺度滲流及裂縫應力敏感效應的非穩(wěn)態(tài)滲流方程,進一步推導出無限大頁巖氣藏非垂直壓裂水平產量遞減模型,并通過Stehfest數值反演及Visual Studio 2012軟件編程對產量遞減規(guī)律進行敏感性分析。同時也對頁巖氣藏產量預測方法進行了相關研究,深入分析各預測模型建立的理論基礎,參數取值范圍和遞減率變化規(guī)律,通過實例計算分析了擬合時長對預測結果的影響,并基于實際應用過程中發(fā)現的問題給出了相應的修正及優(yōu)化方法。通過對上述內容研究之后,得到以下認識及結論:(1)頁巖中礦物含量的相對大小,會直接影響頁巖氣的儲集和儲層縫隙的發(fā)育情況,黏土礦物含量越多,提供的吸附表面積就越多,有利于頁巖氣儲集,而脆性礦物含量越多,越有利于儲層微裂縫的發(fā)育,對氣體滲流有著重要的意義。(2)頁巖基質孔徑大小多處于微米級和納米級,使氣體滲流呈現微尺度效應,滑脫效應和擴散作用對滲流的影響不可忽略,以氣體分子與孔隙壁面碰撞為系數,得到頁巖基質氣體滲流的表觀滲透率數學關系式,同時以平板縫模型建立了裂縫滲透率變化關系式。(3)綜合考慮頁巖基質多尺度滲流、解吸作用及裂縫應力敏感效應,建立了頁巖氣藏雙重介質非穩(wěn)態(tài)滲流方程,通過數學變換得到無限大非垂直壓裂水平井產量遞減模型,應用Visual Studio 2012編程計算,分析各因素對產量遞減規(guī)律的影響,結果表明:儲容比越大,初期產量就越高,產量遞減越慢;不考慮吸附作用和考慮吸附作用主要會影響竄流階段之后的滲流階段,且吸附作用越強,產量越大,遞減越慢;裂縫數量會影響整個滲流階段,且裂縫條數越多,產量就越大;裂縫半長越大,初期產量越高;基質滲透率修正系數越大,產量越大,遞減越慢;而裂縫應力敏感效應主要影響生產后期,滲透率模型越大,產量遞減越快。(4)擬合時間越長,模型預測結果越準確,擬合時長較短時,Duong模型預測結果相對較為準確,PLE模型次之,SEPD模型較差;隨著擬合時長增加,PLE模型預測誤差迅速減小。PLE模型在擬合求解參數時,若不定義參數的取值范圍,有可能會導致計算出的參數值出現錯誤;Duong模型累計產量關系式中,參數q∞并不是定值而是隨時間變化的變量。為減少預測結果的風險,基于組合理論提出頁巖氣藏最優(yōu)組合產量預測方法,并通過實例計算驗證了該方法的可行性。
[Abstract]:In the current international energy supply and demand situation, the effective exploitation of new energy is of great significance to the national strategic deployment, and shale gas as a new unconventional energy, especially after the successful development of North American countries, Based on the reservoir characteristics and percolation law of shale gas reservoir, the change characteristics of apparent permeability and fracture permeability of shale matrix are analyzed. The unsteady seepage equation considering gas multi-scale seepage and fracture stress sensitivity in shale matrix is established, and the non-vertical fracturing horizontal production decline model of infinite shale gas reservoir is further deduced. Through Stehfest numerical inversion and Visual Studio 2012 software programming, sensitivity analysis of production decline law is carried out. At the same time, the production prediction method of shale gas reservoir is studied, and the theoretical foundation of each prediction model is deeply analyzed. The variation law of parameter range and decline rate is analyzed. The effect of fitting time on the prediction results is analyzed by an example. The corresponding correction and optimization methods are given based on the problems found in the practical application. After studying the above contents, the following conclusions are obtained: the relative size of mineral content in shale. It will directly affect the reservoir of shale gas and the development of reservoir crevice. The more clay mineral content, the more adsorption surface area will be provided, which is beneficial to shale gas reservoir, and the more brittle mineral content, the more favorable to the development of reservoir microfractures. The pore size of shale matrix is mostly in the micrometer and nanometer order, which makes the gas percolation appear microscale effect, and the influence of slippage effect and diffusion action on the percolation can not be ignored. Taking the collision of gas molecules with pore wall as the coefficient, the mathematical expression of apparent permeability of shale matrix gas seepage is obtained. At the same time, based on the flat fracture model, the relationship between fracture permeability and fracture permeability is established, and the multiscale seepage of shale matrix is considered synthetically. The unsteady seepage equation of shale gas reservoir with dual medium is established by desorption and fracture stress sensitive effect. The production decline model of infinite non-vertical fracturing horizontal well is obtained by mathematical transformation. The calculation is programmed by Visual Studio 2012. By analyzing the influence of various factors on the law of production decline, the results show that the higher the ratio of storage to capacity, the higher the initial production and the slower the decline of production, and the failure to consider adsorption and adsorption will mainly affect the percolation stage after the channeling stage. And the stronger the adsorption action, the larger the yield, the slower the decline, the more the number of fractures will affect the whole seepage stage, and the more the number of fractures, the larger the yield, the larger the fracture half length, the higher the initial production, the greater the matrix permeability correction coefficient, the greater the yield. The effect of fracture stress sensitivity mainly affects the later stage of production, the larger the permeability model is, the faster the production decline is, the longer the fitting time is, the more accurate the prediction results are. With the increase of fitting time, the prediction error of PLE model decreases rapidly. When fitting and solving parameters, if the range of parameters is not defined, the prediction results of Duong model with shorter fitting time are less accurate than that of SEPD model. In the cumulative output relation of Duong model, the parameter Q 鈭，

本文編號：1518715