本文關鍵詞：通道壓裂中纖維輔助攜砂機理研究　出處：《西南石油大學》2017年博士論文　論文類型：學位論文

  更多相關文章： 通道壓裂 纖維輔助攜砂 壓裂液流變性 三相流動模型 CFD-DEM耦合

【摘要】：通道壓裂技術(Channel Fracturing)是通過交替泵注含支撐劑和不含支撐劑脈沖段,在裂縫中形成不連續(xù)支撐劑團狀鋪置的新型壓裂技術;較于常規(guī)壓裂技術,該技術能有效降低支撐劑用量、提高改造效果�，F(xiàn)場實踐和室內(nèi)實驗表明纖維能提高支撐劑團穩(wěn)定性、降低支撐劑沉降速度,是實現(xiàn)通道壓裂的關鍵。目前,對于纖維輔助攜砂機理研究處于初期,對纖維作用下支撐劑輸送機理認識不清,導致施工參數(shù)無法定量優(yōu)化。因此,本文在纖維基本物理性質(zhì)及其對壓裂液流變性影響研究的基礎上,進一步開展了壓裂液-支撐劑-纖維三相耦合流動的數(shù)值模擬研究,并通過纖維作用下支撐劑大尺度輸送實驗進行驗證,最終對通道壓裂施工參數(shù)進行了優(yōu)化。通過纖維分散性實驗和穩(wěn)定性實驗,對纖維基本物理性質(zhì)進行了分析;在此基礎上,通過壓裂液流變實驗和電鏡掃描實驗,研究了纖維對壓裂液基液和凍膠壓裂液微觀結構、表觀粘度以及粘彈性的影響規(guī)律。實驗結果表明:纖維具有大長徑比、均勻分散、化學穩(wěn)定的特征,在壓裂液中以固相形態(tài)存在,纖維之間相互接觸少;纖維能促進胍膠分子鏈網(wǎng)絡結構形成,使得壓裂液基液表觀粘度明顯增加,其增量受到纖維濃度、稠化劑濃度、剪切速率以及溫度的影響;凍膠壓裂液胍膠分子鏈網(wǎng)絡結構本身強度較高,纖維對凍膠壓裂液表觀粘度的影響較小,但會一定程度提高其彈性模量�；陔x散元方法(DEM),考慮壓裂液曳力、浮力以及支撐劑與纖維之間的相互作用力,分別建立纖維運動模型和支撐劑運動模型;基于計算流體力學(CFD),考慮支撐劑和纖維對壓裂液流動的影響,建立三相耦合的壓裂液流動模型;耦合上述三個模型,得到壓裂液-支撐劑-纖維三相耦合流動模型。分別采用相耦合的SIMPLE算法、顯示差分法對液相、固相運動方程進行求解,通過纖維壓裂液中顆粒沉降實驗驗證了該模型的正確性。采用建立的壓裂液-支撐劑-纖維三相耦合流動模型,開展單支撐劑和單纖維、單支撐劑和多纖維以及支撐劑團沉降模擬,研究了纖維輔助機理。模擬結果表明,纖維通過與支撐劑的物理碰撞約束支撐劑的運動,該約束作用受到碰撞位置、纖維取向、纖維濃度和長度的影響。碰撞使得纖維發(fā)生運動,纖維之間相互作用增強、接觸數(shù)量增多,多根纖維相互接觸形成網(wǎng)狀結構,大大降低支撐劑運動速度。纖維通過與支撐劑以及纖維之間的碰撞,將支撐劑團外圍支撐劑受到的壓裂液曳力,傳遞給內(nèi)部其他支撐劑,使得支撐劑之間速度差異減小,提高支撐劑團的穩(wěn)定性。開展了纖維作用下支撐劑大尺度輸送實驗,結合壓裂液流變實驗結果和纖維輔助攜砂機理分析結果,驗證了工程條件下纖維對支撐劑團輸送的作用機理,并進一步對通道壓裂施工參數(shù)優(yōu)化開展了研究。實驗結果表明,纖維、壓裂液、泵注參數(shù)是通道壓裂支撐劑輸送形態(tài)的關鍵控制因素。對比分析支撐劑輸送形態(tài)和通道特征,確定了最優(yōu)脈沖單元注入?yún)?shù)區(qū)間,建立了施工排量和脈沖時間優(yōu)化圖版,為通道壓裂施工參數(shù)優(yōu)化提供了指導。本文揭示了纖維輔助攜砂機理,可為通道壓裂工藝參數(shù)優(yōu)化、壓裂液、支撐劑和纖維優(yōu)選提供有效指導。
[Abstract]:Channel (Channel Fracturing) fracturing technology by alternating injection pump containing proppant and without proppant fracturing technology to form a new type of pulse, discontinuous proppant slug laid in cracks; compared with the conventional fracturing technology, this technology can effectively reduce the amount of proppant, improve the modification effect. The field practice and indoor experiment show that the fiber can improve the proppant mass stability, reduce the proppant settling velocity is a key channel for fracturing. At present, fiber assisted sand carrying mechanism research in the early stage, the fiber under the action of proppant transport mechanism is unclear, leading to quantitative optimization of construction parameters. Therefore, based on the basic physical properties of fracturing and fiber effects of fluid rheology on the basis of the further development of the proppant fracturing fluid - - fiber three-phase coupling flow numerical simulation research, and through the fiber under the action of supporting large scale transport agent Send the experimental verification, the final parameters of channel fracturing were optimized. Experiment and stability experiment of fiber fiber dispersion, basic physical properties are analyzed; on this basis, the fracturing fluid rheology experiment and scanning electron microscopy experiments, effects of fiber on fracturing fluid base fluid and fracturing fluid micro structure, table influence of viscosity and viscoelasticity. The experimental results show that the fiber has a high aspect ratio, uniform dispersion, stable chemical characteristics, with solid morphology in fracturing fluid, contact between fibers; fiber can promote the formation of guar gum molecular chain network structure, make the fracturing fluid liquid apparent viscosity increased significantly and the increment by fiber concentration, thickener concentration, shear rate and temperature effects; frozen guar gum fracturing fluid high molecular chain network structure strength, fiber to freeze the apparent viscosity of gum fracturing fluid Little effect, but will be increased to a certain extent. The elastic modulus of the discrete element method (DEM), based on the consideration of the fracturing fluid drag, buoyancy and interaction between proppant and fiber, respectively establish fiber motion model and proppant motion model; based on computational fluid dynamics (CFD), considering the influence of fiber on the proppant and fracturing fluid the flow of fracturing fluid flow model of three-phase coupling; coupling of the above three models, get the proppant fracturing fluid - - fiber three-phase coupling flow model. Using SIMPLE coupling algorithm, display difference method of liquid phase, solid phase flow equations are solved by experiment of particle deposition in the fracturing fluid to verify the fiber the model is established. Using the proppant fracturing fluid - - fiber coupling three-phase flow model, carry out single proppant and single fiber, single and multi fiber proppant and proppant sedimentation simulation research group, fiber Dimensional auxiliary mechanism. The simulation results show that the fiber with physical collision proppant constrained proppant movement, collision position, the constraint is affected by fiber orientation, fiber density and length. The fiber collision motion, and enhanced the interaction between fibers, contact number, a plurality of fibers in contact with each other to form a network structure, greatly reduce the proppant velocity. The collision between the fiber and fiber with proppant, will support the fracturing fluid drag agent by peripheral supporting agent, transfer to other internal supporting agent, makes the speed difference between the proppant decrease, improve the stability of proppant group. Carried out under the action of large scale fiber proppant transport experiment according to the experimental results, the analysis results of fracturing fluid rheology and fiber assisted sand carrying mechanism, to verify the mechanism of fiber proppant transport group engineering conditions, and a Step on channel fracturing parameter optimization was studied. The experimental results show that the fiber, fracturing fluid, injection parameter is fracturing proppant transport channel form the key control factors. Comparative analysis of proppant transport form and channel characteristics, to determine the optimal injection parameters of unit pulse interval, established construction displacement and pulse time optimization chart provide guidance for the optimization of construction parameters of fracturing channel. This paper reveals the fiber assisted sand carrying mechanism, optimization, channel fracturing parameter of fracturing fluid, proppant and fibers preferably provide effective guidance.

【學位授予單位】：西南石油大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TE357

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