【摘要】：基質(zhì)酸化作為油氣井增產(chǎn)和注水井增注的重要措施,在石油天然氣勘探開發(fā)中具有重要作用。碳酸鹽巖儲層中往往都會有微裂縫的存在,并且由于地質(zhì)情況復(fù)雜多變,微裂縫的形態(tài)和分布也是非常復(fù)雜的。雖然生產(chǎn)過程中多數(shù)的微裂縫幾乎不對儲層流體的流動作貢獻,但酸化作業(yè)可能使其中某些微裂縫與井相互連通形成高滲通道。然而,以往的學(xué)者在對碳酸鹽巖儲層中的酸化過程進行模擬和計算時,往往未考慮微裂縫的存在,或是將裂縫考慮為規(guī)則的形狀,明顯與實際不符。另外,碳酸鹽巖酸化存在一個最優(yōu)注酸速率,在該速率下,突破(breakthrough)時所需的酸液量最少。所以,為了深入認識裂縫性碳酸鹽巖酸化的特點,優(yōu)選施工參數(shù),急需尋求一種更好更切合實際的理論或方法來模擬裂縫性碳酸鹽巖中的酸液流動反應(yīng)過程。 本文首次將有限單元法用于研究雙重尺度模型,并通過有限元網(wǎng)格對裂縫性碳酸鹽巖求解域進行精細網(wǎng)格劃分,模擬了酸液在其中的流動反應(yīng)過程。通過模擬結(jié)果討論了注酸速率、裂縫長度、裂縫方位角和裂縫離井的距離等因素對酸化效果的影響,并進行了實例計算。具體研究工作如下： (1)系統(tǒng)調(diào)研了國內(nèi)外裂縫性碳酸鹽巖酸化的數(shù)學(xué)模型和模擬方法,在此基礎(chǔ)上全面總結(jié)了碳酸鹽巖酸化的特點以及裂縫對其的影響,深入研究了各種模型和方法的不足與優(yōu)點。 (2)為研究酸液在含微裂縫的儲層中的流動反應(yīng)規(guī)律,將微裂縫假設(shè)為高孔高滲幾何形態(tài)特殊的區(qū)域,通過雙重尺度模型表征酸液流動反應(yīng)的物理化學(xué)過程。 (3)通過有限元軟件生成裂縫性碳酸鹽巖物理模型,并將得到的單元、節(jié)點信息轉(zhuǎn)換為可編程計算的數(shù)據(jù)形式。按照有限元的理論對數(shù)學(xué)模型離散化處理,建立了對應(yīng)的可用于計算機模擬計算的數(shù)值模型。 (4)用Matlab編寫了計算程序,模擬了酸液在裂縫性碳酸鹽巖中的流動反應(yīng)過程,討論了注酸速率、酸液用量、裂縫長度、裂縫方位角和裂縫與井的距離等因素對酸化效果的影響。 (5)根據(jù)具體油田資料生成離散裂縫網(wǎng)絡(luò)模型,在整個油藏尺度上進行了單井酸化模擬,深化了理論研究的實際意義。 本論文完成的研究內(nèi)容以及所取得的系列初步研究成果,實現(xiàn)了對裂縫性碳酸鹽巖儲層的酸化模擬的研究,探討了裂縫參數(shù)對酸化效果的影響,證明了有限單元法用以酸化模擬的可行性,是數(shù)值模擬發(fā)展的一個重要方向,為多孔介質(zhì)內(nèi)的精細酸化模擬提供了一個新的嘗試。
[Abstract]:As an important measure for increasing oil and gas production and injection, matrix acidification plays an important role in oil and gas exploration and development. Microfractures often exist in carbonate reservoirs, and the morphology and distribution of microfractures are very complicated because of the complex geological conditions. Although most of the microfractures in the production process make little contribution to the fluid flow in the reservoir, acidizing operations may make some of the microfractures and wells connected to each other to form high permeability channels. However, in the simulation and calculation of acidizing process in carbonate reservoirs, previous scholars often did not consider the existence of micro-fractures or the shape of fractures as regular, which is obviously not in accordance with the actual situation. In addition, there is an optimal rate of acid injection for acidification of carbonate rocks, at which the amount of acid needed to break through (breakthrough) is the least. Therefore, in order to deeply understand the characteristics of fractured carbonate rock acidification and optimize construction parameters, it is urgent to find a better and more practical theory or method to simulate the process of acid flow reaction in fractured carbonate rock. In this paper, the finite element method (FEM) is used to study the dual scale model for the first time. The fluid reaction process of acid in the solution domain of fractured carbonate rock is simulated by the finite element method (FEM). The effects of acid injection rate, fracture length, fracture azimuth angle and fracture distance from well on acidizing effect are discussed. The specific research works are as follows: (1) the mathematical models and simulation methods of fractured carbonate rock acidification at home and abroad are systematically investigated, and on this basis, the characteristics of carbonate acidification and the influence of fractures on it are summarized. The shortcomings and advantages of various models and methods are studied in depth. (2) in order to study the flow response of acid in reservoirs containing micro-fractures, the micro-fractures are assumed to be special areas with high porosity and high permeability. The physical and chemical process of acid flow reaction is characterized by a dual scale model. (3) the physical model of fractured carbonate rock is generated by finite element software and the unit node information is converted into programmable data form. According to the finite element theory, the mathematical model is discretized, and the corresponding numerical model can be used for computer simulation. (4) the calculation program is written with Matlab. The flow reaction process of acid in fractured carbonate rock is simulated. The acid injection rate, acid dosage, fracture length are discussed. The influence of fracture azimuth and the distance between fracture and well on acidizing effect. (5) according to the specific oilfield data, the discrete fracture network model is generated, and the acidizing simulation of single well is carried out on the whole reservoir scale. It deepens the practical significance of theoretical research. The research content and series of preliminary research results achieved in this paper have realized the study of acidizing simulation of fractured carbonate reservoir and discussed the influence of fracture parameters on acidizing effect. The feasibility of the finite element method for acidizing simulation is proved, which is an important direction in the development of numerical simulation and provides a new attempt for fine acidification simulation in porous media.
【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】：TE357.2

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