【摘要】：水力壓裂可顯著提高頁巖氣等致密儲層巖體的滲透性以增加油氣產(chǎn)量,然而受多因素影響,水力壓裂形成縫網(wǎng)結構的機理和壓裂優(yōu)化設計一直是研究的焦點和難點。本研究基于滲流-應力-破壞耦合計算模擬方法,對不同水力加載條件下的非均質儲層水力壓裂過程進行了模擬和對比研究。研究結果表明:水力壓裂過程中起始注水壓力和增量大小對水力壓裂縫網(wǎng)擴展和改造區(qū)域形態(tài)有著顯著的影響。當起始注水壓力小于等于模型材料體抗拉強度,并緩慢增壓致裂時,壓裂過程可近似視為穩(wěn)態(tài)應力-破壞-滲流耦合作用過程的不同階段,這種情況下僅在壓裂井孔周圍形成兩組對稱式的傘狀水力裂縫帶。當對模型體施加高于模型材料體破裂壓力的注水壓力時,相當于對壓裂孔快速施加高動水壓力,水力裂縫沿壓裂孔全方位迅速萌生并快速擴展,當注水壓力值高于破裂壓力一定幅值時,壓裂改造可形成圍繞壓裂井全方位的放射狀裂縫網(wǎng)絡,使壓裂儲層得以最大范圍改造。在擬靜力和擬動力兩種加載條件下,不同水巖相互作用機理是造成不同水力加載條件出現(xiàn)不同縫網(wǎng)結構的力學機制,而對于實際的頁巖氣儲層改造,壓裂產(chǎn)生圍繞壓裂井全方位放射狀的縫網(wǎng)結構則是一種最優(yōu)的體積壓裂改造。
[Abstract]:Hydraulic fracturing can significantly improve the permeability of tight rock mass, such as shale gas, in order to increase oil and gas production. However, due to the influence of many factors, the mechanism of hydraulic fracturing forming fracture network structure and the optimum design of fracturing have been the focus and difficulty of the research. Based on the coupled seepage stress-failure simulation method, the hydraulic fracturing process of heterogeneous reservoir under different hydraulic loading conditions was simulated and compared. The results show that the initial injection pressure and increment have a significant effect on the extension and reconstruction of hydraulic fracturing network in the process of hydraulic fracturing. When the initial injection pressure is less than or equal to the tensile strength of the model material and the fracture is caused by a slow increase of pressure, the fracturing process can be approximately regarded as the different stages of the steady state stress-failure seepage coupling process. In this case, only two sets of symmetrical umbrella hydraulic fracture zones are formed around the fracturing well hole. When the water injection pressure of the model body is higher than the fracture pressure of the model material body, it is equivalent to applying high dynamic water pressure to the fracturing hole quickly, and the hydraulic fracture is springing up and expanding rapidly along the fracturing hole. When the value of water injection pressure is higher than a certain amplitude of fracture pressure, the radial fracture network around the fracturing well can be formed by fracturing reconstruction, and the maximum range of fracturing reservoir can be reconstructed. Under two loading conditions, pseudostatic and pseudo-dynamic, different water-rock interaction mechanism is the mechanical mechanism which results in different fracture network structure under different hydraulic loading conditions, but for the actual shale gas reservoir transformation, Fracturing is a kind of optimal volume fracturing.
【作者單位】： 中國科學院地質與地球物理研究所中國科學院頁巖氣與地質工程重點實驗室;中國科學院大學;
【基金】：中國科學院戰(zhàn)略性先導科技專項(B類)(XDB10030602) 國家自然科學基金項目(41372325,41372323,41402280)資助
【分類號】：TE357.1
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本文編號：2171564