煤層氣直井水力波及壓裂可行性論證
發(fā)布時間：2019-05-10 10:38
【摘要】：煤層氣作為一種優(yōu)質(zhì)、清潔的非常規(guī)天然氣資源,倍受國內(nèi)外學(xué)者廣泛關(guān)注。國內(nèi)煤層氣資源量豐富,煤層氣高效開發(fā)利用在環(huán)境保護(hù)、能源保障和經(jīng)濟(jì)發(fā)展等方面具有重要意義。我國煤層氣儲層低壓、低孔、低滲等特點(diǎn)決定了煤層氣井鉆完井后普遍需要增產(chǎn)才能產(chǎn)氣,但現(xiàn)有增產(chǎn)技術(shù)對煤層氣產(chǎn)量提高效果較差,不能實(shí)現(xiàn)煤層氣高效經(jīng)濟(jì)開采。分析發(fā)現(xiàn),煤層氣以吸附氣為主的賦存方式、以降壓解吸為主的生產(chǎn)特點(diǎn)及煤層氣儲層低孔、低滲的地質(zhì)特征決定了提高煤層氣產(chǎn)量的關(guān)鍵在于增大裂縫網(wǎng)絡(luò)與煤巖基質(zhì)的接觸面積,而煤巖中發(fā)育的面、端割理系統(tǒng)為裂縫網(wǎng)絡(luò)的形成提供了必要條件。 基于此,本文在前人研究基礎(chǔ)之上,綜合運(yùn)用巖石力學(xué)、彈性力學(xué)、斷裂力學(xué)、流體力學(xué)、水力壓裂力學(xué)、高等數(shù)學(xué)和計(jì)算機(jī)編程等多學(xué)科知識,以增大煤層氣藏增產(chǎn)改造體積波及范圍為目標(biāo)進(jìn)行研究,取得了以下主要成果及認(rèn)識： (1)深入分析了煤層氣儲層工程地質(zhì)特征和現(xiàn)有增產(chǎn)措施工藝原理、技術(shù)特點(diǎn)及存在的不足,提出了利用縫間應(yīng)力干擾作用增大煤層氣藏增產(chǎn)改造體積波及范圍的煤層氣直井水力波及壓裂工藝技術(shù),建立了兩口正對的煤層氣直井水力波及壓裂物理模型。 (2)推導(dǎo)了適用于分析水力波及壓裂多裂縫產(chǎn)生的應(yīng)力擾動問題的位移不連續(xù)數(shù)值計(jì)算方法及其求解步驟,利用MATLAB編程,對比分析了單一壓裂主縫和水力波及壓裂主縫縫間應(yīng)力干擾作用的差異,劃分出了近場復(fù)雜縫網(wǎng)和遠(yuǎn)場復(fù)雜縫網(wǎng),分析了水力波及壓裂縫間應(yīng)力干擾作用對復(fù)雜縫網(wǎng)形成的影響；研究了壓裂裂縫半縫長、縫內(nèi)凈壓力、煤巖泊松比和井間距對水力波及壓裂應(yīng)力干擾作用的影響規(guī)律。 (3)分析了誘導(dǎo)煤層氣儲層中面、端割理系統(tǒng)破壞形成分支裂縫的最大縫內(nèi)凈壓力與地應(yīng)力差的關(guān)系以及分支裂縫延伸至單井壓裂時的應(yīng)力各向同性點(diǎn)以后的延伸方向,證明了煤層氣直井水力波及壓裂有利于復(fù)雜縫網(wǎng)的形成。 (4)利用二維離散元分析軟件UDEC編程,對比分析了單口煤層氣直井壓裂和兩口正對的煤層氣直井水力波及壓裂裂縫網(wǎng)絡(luò)擴(kuò)展形態(tài),論證了煤層氣直井水力波及壓裂增大煤層氣藏增產(chǎn)改造體積波及范圍的可行性；研究了初始水平主應(yīng)力差、煤巖泊松比、井間距、壓裂主縫半縫長和壓裂液黏度對水力波及壓裂縫網(wǎng)擴(kuò)展形態(tài)的影響規(guī)律。 通過本文的研究,論證了煤層氣直井水力波及壓裂相比于單獨(dú)壓裂能進(jìn)一步增大煤層氣藏增產(chǎn)改造體積波及范圍,敏感性參數(shù)分析對水力波及壓裂施工設(shè)計(jì)和井層優(yōu)選具有指導(dǎo)意義,近場復(fù)雜縫網(wǎng)和遠(yuǎn)場復(fù)雜縫網(wǎng)分區(qū)為下步經(jīng)濟(jì)優(yōu)化提供了方向。
[Abstract]:As a kind of high quality and clean unconventional natural gas resources, coalbed methane (CBM) has been widely concerned by scholars at home and abroad. The resources of coal bed methane are abundant in our country. The efficient exploitation and utilization of coal bed methane is of great significance in environmental protection, energy security and economic development. The characteristics of low pressure, low porosity and low permeability of coalbed methane reservoir in China determine that it is generally necessary to increase gas production after drilling, but the existing production increasing technology has poor effect on increasing coalbed methane production and can not realize high efficiency and economic exploitation of coalbed methane. It is found that the coalbed methane occurs mainly by adsorptive gas, and the production characteristics of low porosity of coalbed methane reservoir are mainly characterized by depressurization and desorption. The geological characteristics of low permeability determine that the key to improve the production of coalbed methane lies in increasing the contact area between fracture network and coal and rock matrix, and the surface and end cutting system developed in coal and rock provide the necessary conditions for the formation of fracture network. Based on this, on the basis of previous studies, this paper makes comprehensive use of rock mechanics, elasticity, fracture mechanics, fluid mechanics, hydraulic fracturing mechanics, advanced mathematics and computer programming. The main achievements and understandings are as follows: (1) the engineering geological characteristics of coalbed methane reservoir and the principle of existing measures for increasing production are analyzed in depth, and the main achievements and understandings are as follows: (1) the engineering geological characteristics of coalbed methane reservoir and the principle of existing measures to increase production are deeply analyzed. The technical characteristics and existing shortcomings are put forward, and the hydraulic and fracturing technology of coalbed methane vertical well is put forward to increase the volume and range of production increase and transformation of coalbed methane gas reservoir by using the effect of interfracture stress interference. The physical models of hydraulic and fracturing of two straight wells of coalbed methane are established. (2) the numerical calculation method of displacement discontinuity and its solving steps are derived, which are suitable for analyzing the stress disturbance caused by hydraulic and fracturing multiple cracks. The method is programmed by MATLAB. The difference of stress interference between single fracturing main seam and hydraulic fracture main seam is compared and analyzed, and the near field complex seam net and far field complex joint net are divided. The influence of stress interference between hydraulic and pressure cracks on the formation of complex seam network is analyzed. The effects of half fracture length, net pressure in fracture, Poisson's ratio of coal to rock and well spacing on hydraulic and fracturing stress are studied. (3) the relationship between the maximum fracture net pressure and the ground stress difference caused by the failure of the end cutting system in the induced coalbed methane reservoir is analyzed, and the extension direction of the stress isotropism point when the branch fracture extends to the single well fracturing is analyzed. It is proved that hydraulic and fracturing in straight wells of coalbed methane is beneficial to the formation of complex fracture network. (4) using two-dimensional discrete element analysis software UDEC programming, the hydraulic and fracture network expansion patterns of single coalbed methane straight well and two positive coalbed methane straight wells are compared and analyzed. It is proved that it is feasible for straight well hydraulic and fracturing of coalbed methane to increase the volume and range of stimulation and reconstruction of coalbed gas. The effects of initial horizontal principal stress difference, Poisson's ratio of coal to rock, well spacing, half fracture length of main fracture and viscosity of fracturing fluid on the propagation pattern of hydraulic and fracturing fracture pattern are studied. Through the study of this paper, it is proved that hydraulic and fracturing in straight wells of coalbed methane can further increase the volume spread range of production increase and transformation of coalbed methane reservoirs compared with single fracturing. The analysis of sensitivity parameters is of guiding significance for hydraulic and fracturing construction design and well layer optimization. The division of near-field complex fracture network and far-field complex joint network provides a direction for the next step of economic optimization.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TE357
本文編號：2473584
[Abstract]:As a kind of high quality and clean unconventional natural gas resources, coalbed methane (CBM) has been widely concerned by scholars at home and abroad. The resources of coal bed methane are abundant in our country. The efficient exploitation and utilization of coal bed methane is of great significance in environmental protection, energy security and economic development. The characteristics of low pressure, low porosity and low permeability of coalbed methane reservoir in China determine that it is generally necessary to increase gas production after drilling, but the existing production increasing technology has poor effect on increasing coalbed methane production and can not realize high efficiency and economic exploitation of coalbed methane. It is found that the coalbed methane occurs mainly by adsorptive gas, and the production characteristics of low porosity of coalbed methane reservoir are mainly characterized by depressurization and desorption. The geological characteristics of low permeability determine that the key to improve the production of coalbed methane lies in increasing the contact area between fracture network and coal and rock matrix, and the surface and end cutting system developed in coal and rock provide the necessary conditions for the formation of fracture network. Based on this, on the basis of previous studies, this paper makes comprehensive use of rock mechanics, elasticity, fracture mechanics, fluid mechanics, hydraulic fracturing mechanics, advanced mathematics and computer programming. The main achievements and understandings are as follows: (1) the engineering geological characteristics of coalbed methane reservoir and the principle of existing measures for increasing production are analyzed in depth, and the main achievements and understandings are as follows: (1) the engineering geological characteristics of coalbed methane reservoir and the principle of existing measures to increase production are deeply analyzed. The technical characteristics and existing shortcomings are put forward, and the hydraulic and fracturing technology of coalbed methane vertical well is put forward to increase the volume and range of production increase and transformation of coalbed methane gas reservoir by using the effect of interfracture stress interference. The physical models of hydraulic and fracturing of two straight wells of coalbed methane are established. (2) the numerical calculation method of displacement discontinuity and its solving steps are derived, which are suitable for analyzing the stress disturbance caused by hydraulic and fracturing multiple cracks. The method is programmed by MATLAB. The difference of stress interference between single fracturing main seam and hydraulic fracture main seam is compared and analyzed, and the near field complex seam net and far field complex joint net are divided. The influence of stress interference between hydraulic and pressure cracks on the formation of complex seam network is analyzed. The effects of half fracture length, net pressure in fracture, Poisson's ratio of coal to rock and well spacing on hydraulic and fracturing stress are studied. (3) the relationship between the maximum fracture net pressure and the ground stress difference caused by the failure of the end cutting system in the induced coalbed methane reservoir is analyzed, and the extension direction of the stress isotropism point when the branch fracture extends to the single well fracturing is analyzed. It is proved that hydraulic and fracturing in straight wells of coalbed methane is beneficial to the formation of complex fracture network. (4) using two-dimensional discrete element analysis software UDEC programming, the hydraulic and fracture network expansion patterns of single coalbed methane straight well and two positive coalbed methane straight wells are compared and analyzed. It is proved that it is feasible for straight well hydraulic and fracturing of coalbed methane to increase the volume and range of stimulation and reconstruction of coalbed gas. The effects of initial horizontal principal stress difference, Poisson's ratio of coal to rock, well spacing, half fracture length of main fracture and viscosity of fracturing fluid on the propagation pattern of hydraulic and fracturing fracture pattern are studied. Through the study of this paper, it is proved that hydraulic and fracturing in straight wells of coalbed methane can further increase the volume spread range of production increase and transformation of coalbed methane reservoirs compared with single fracturing. The analysis of sensitivity parameters is of guiding significance for hydraulic and fracturing construction design and well layer optimization. The division of near-field complex fracture network and far-field complex joint network provides a direction for the next step of economic optimization.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TE357
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