本文選題：多薄層 + 裂縫擴(kuò)展　； 參考：《西南石油大學(xué)》2015年碩士論文

【摘要】：樁23北區(qū)位于山東省東營市河口區(qū)東北部潮間沼澤地帶,為典型多薄層,具有低孔低滲,小層眾多,儲(chǔ)隔層物性差異大,開采難度大等特點(diǎn),常采用籠統(tǒng)壓裂或分層壓裂進(jìn)行增產(chǎn)。該區(qū)壓裂易形成垂直縫,存在裂縫形態(tài)預(yù)測不準(zhǔn)確,裂縫高度過度增長,多縫干擾機(jī)理不明確等問題。因此,有必要對該區(qū)裂縫擴(kuò)展規(guī)律展開研究,準(zhǔn)確預(yù)測裂縫擴(kuò)展形態(tài),以控制裂縫高度,防止裂縫相互連接為目的,指導(dǎo)該區(qū)壓裂優(yōu)化設(shè)計(jì)。 本文基于有限元方法,推導(dǎo)了巖體滲流應(yīng)力耦合方程組,基于損傷力學(xué),結(jié)合黏彈性損傷cohesive單元,建立裂縫中流體切向、法向流動(dòng)模型及裂縫起裂和擴(kuò)展準(zhǔn)則,引入無量綱損傷因子D表征裂縫起裂損傷,實(shí)現(xiàn)滲流應(yīng)力損傷耦合裂縫擴(kuò)展數(shù)值模擬�；谏鲜鰸B流應(yīng)力損傷耦合數(shù)值模擬方法,以大型商業(yè)有限元軟件ABAQUS為依托,針對樁23北區(qū)典型井X,建立多薄層二維裂縫動(dòng)態(tài)擴(kuò)展有限元模型,對二維裂縫形態(tài)、誘導(dǎo)應(yīng)力和多縫干擾規(guī)律進(jìn)行研究；在此基礎(chǔ)上,進(jìn)一步建立多薄層三維裂縫動(dòng)態(tài)擴(kuò)展有限元模型,對三維裂縫形態(tài)演化和多縫干擾規(guī)律進(jìn)行研究,最終實(shí)現(xiàn)了樁23北區(qū)多薄層裂縫擴(kuò)展規(guī)律研究。通過研究主要取得了以下成果和認(rèn)識(shí)： (1)采用滲流應(yīng)力損傷耦合方法,建立了多薄層全三維裂縫動(dòng)態(tài)擴(kuò)展有限元模型,精確表征儲(chǔ)隔層材料非均質(zhì)性,實(shí)現(xiàn)滲流-應(yīng)力-損傷三場耦合,真實(shí)還原裂縫三維形態(tài)演化。 (2)裂縫擴(kuò)展形態(tài)主要受地層參數(shù)包括地應(yīng)力、抗拉強(qiáng)度、楊氏模量和臨界能量釋放率以及施工參數(shù)包括施工排量和壓裂液黏度等控制。具有高最小水平主應(yīng)力、高抗拉強(qiáng)度、高臨界能量釋放率和低楊氏模量的隔層以及低排量和低壓裂液粘度能控制裂縫高度,防止裂縫相互連接。 (3)修改軟件內(nèi)置程序,設(shè)定多裂縫同時(shí)或先后擴(kuò)展,實(shí)現(xiàn)籠統(tǒng)壓裂和分層壓裂裂縫擴(kuò)展數(shù)值模擬；基于分層壓裂,調(diào)整網(wǎng)格節(jié)點(diǎn)坐標(biāo),實(shí)現(xiàn)不同隔層厚度下裂縫干擾規(guī)律分析。 (4)籠統(tǒng)壓裂較分層壓裂裂縫干擾更強(qiáng)烈,縫高更大,縫長更小、誘導(dǎo)應(yīng)力更大,在壓裂初期裂縫即相互連接；為控制裂縫高度防止裂縫連接,應(yīng)優(yōu)選分層壓裂進(jìn)行施工作業(yè)。 (5)分層壓裂時(shí),隔層厚度小于3.6m,裂縫干擾較大,裂縫相互連接；隔層厚度大于5.6m,裂縫干擾較小,裂縫未相互連接。據(jù)此進(jìn)行分層壓裂段間距優(yōu)化,當(dāng)隔層厚度小于3.6m時(shí),上下合為一段進(jìn)行壓裂；當(dāng)隔層厚度大于5.6m時(shí),則分兩段壓裂。 本文對樁23北區(qū)多薄層裂縫擴(kuò)展規(guī)律進(jìn)行了系統(tǒng)研究,研究成果對于類似多薄層壓裂優(yōu)化設(shè)計(jì)具有一定指導(dǎo)意義。
[Abstract]:Duan 23 North District is located in the northeast tidal swamp zone of Dongying City, Shandong Province. It is a typical multi-thin layer with the characteristics of low porosity and low permeability, numerous small layers, great difference in physical properties of reservoir and septum, and great difficulty in mining, etc. General fracturing or stratified fracturing is often used to increase production. It is easy to form vertical fractures in this area, and there are some problems such as inaccurate prediction of fracture morphology, excessive growth of fracture height, unclear mechanism of multi-fracture interference, and so on. Therefore, it is necessary to study the law of fracture propagation in this area, to accurately predict the shape of fracture propagation, to control the height of fracture and to prevent the fracture from connecting with each other, and to guide the optimum design of fracturing in this area. Based on the finite element method, the coupled equations of seepage and stress in rock mass are derived in this paper. Based on the damage mechanics and viscoelastic damage cohesive element, the tangential and normal flow models and fracture initiation and propagation criteria are established. The dimensionless damage factor D is introduced to characterize the crack initiation damage, and the numerical simulation of seepage stress damage coupled crack propagation is realized. Based on the coupled numerical simulation method of seepage stress and damage, based on the large-scale commercial finite element software ABAQUS, the dynamic finite element model of multi-layer two-dimensional fracture propagation is established for the typical well X23 North District, and the two-dimensional fracture morphology is analyzed. On the basis of this, the dynamic finite element model of multi-thin-layer three-dimensional crack propagation is established, and the three-dimensional fracture morphology evolution and multi-crack interference law are studied. Finally, the fracture propagation law of multi-thin-layer in the north of pile 23 is studied. Through the research, the following results and understandings have been achieved: 1) by using the coupled method of seepage stress and damage, the finite element model of dynamic propagation of multi-thin-layer full-3D fracture is established, which accurately characterizes the heterogeneity of reservoir and compartments, realizes the coupling of seepage, stress-damage, and the true three-dimensional morphological evolution of the reductive fracture. (2) the fracture propagation morphology is mainly controlled by formation parameters including in-situ stress, tensile strength, Young's modulus, critical energy release rate and construction parameters, such as construction displacement and fracturing fluid viscosity. The interlayer with high minimum principal stress, high tensile strength, high critical energy release rate and low Young's modulus, as well as low displacement and low pressure fracturing fluid viscosity, can control the fracture height and prevent the fracture from being connected with each other. 3) modify the software built-in program, set multiple fractures at the same time or successively expand to achieve general fracturing and stratified fracturing fracture expansion numerical simulation, based on stratified fracturing, adjust grid node coordinates, to achieve different thickness of fracture interference law analysis. In general fracturing, the interference of fracture is stronger, the fracture height is larger, the fracture length is smaller, the induced stress is larger than that in stratified fracturing, and the fractures are connected with each other in the early stage of fracturing, and in order to control the fracture height to prevent fracture connection, the operation of stratified fracturing should be optimized. In stratified fracturing, the thickness of the interlayer is less than 3.6 m, the interference of fracture is greater and the fracture is connected with each other, and the thickness of interlayer is more than 5.6 m, the interference of fracture is small, and the fracture is not connected with each other. According to this, the interval of the fracturing interval is optimized, when the thickness of the interval is less than 3.6 m, the upper and lower sections are fracturing in one section, and when the thickness of the interval is more than 5.6 m, the fracturing is divided into two sections. In this paper, the fracture propagation law of multi-thin-layer in Zhuan23bei area is systematically studied, and the research results have certain guiding significance for the optimization design of similar multi-thin-layer fracturing.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TE312

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