低渗透油藏水平井渗流理论及分段完井优化研究

发布时间：2018-05-26 03:00

本文选题：低渗透 + 水平井　；参考：《中国地质大学(北京)》2015年博士论文

【摘要】：低渗透油气藏在我国分布十分广泛,具有巨大的资源潜力。但低渗透油藏流体由于其自身特殊的非线性渗流特征,导致开发难度大,井的产量低。鉴于水平井开发的固有优势,利用水平井开发低渗透油藏在实际生产中得到越来越广泛的应用。然而水平井开采时,受底水或边水的影响,油井生产一段时间后含水上升,形成水体锥进从而影响水平井的开发效果,通常我们采用分段完井的生产方案。本文针对低渗透油藏水平井的分段完井,考虑变盲筛比的分段完井方法,从低渗透油藏水平井的渗流理论及分段完井的优化理论两个方面进行展开,主要完成了以下工作:(1)考虑启动压力梯度,基于微元线汇的思想,利用势的叠加原理和镜像反映原理,分别建立了低渗透封闭油藏、低渗透底水油藏和低渗透边水油藏的分段完井渗流模型。(2)采用带盲管的分段完井方法,盲管和生产水平段在水平井筒上间隔排列,从渗流力学和流体力学的基本定理出发,建立了裸眼完井和射孔完井两种方式下的水平井分段完井井筒压降计算模型。(3)利用耦合连接方程,分别建立了两种完井方式下三种不同边界条件的6个低渗透油藏水平井分段完井油藏/井筒耦合模型。利用实例数据对耦合模型的产能影响因素进行分析,研究结果表明:低渗透油藏水平井的产量随着启动压力梯度的增大而逐渐减小;随着油层厚度的增大逐渐增加,但是增加幅度趋于平缓,这说明在较厚的低渗透油层中利用水平井开发提高产量的能力有限。(4)以水平井的产量作为目标函数,以生产水平井段的长度和中心点位置作为优化变量,分别建立了两种完井方式下三种不同边界条件的6个低渗透油藏水平井分段完井优化模型。并利用遗传算法编制数值模拟软件对其进行了优化求解,分别给出了不同分段模式下的最优分段方案。最后通过设计打开程度、分段数等参数并结合实际油田数据对影响优化模型产能的因素进行了敏感性分析。研究结果表明:对于低渗透封闭油藏水平井筒分段越多,产量越大,但随着生产水平段个数的增加,产量增速趋于平缓。对于低渗透底水油藏和边水油藏随着水平井筒分段数的增加,产量逐渐增大,但产量增加幅度较小,因此对低渗透底水油藏和边水油藏水平井筒分段数对产量的影响较微弱。本文所建立的低渗透油藏水平井分段完井优化理论对低渗透油藏采用分段完井方法进行开采提供了重要的理论支撑,对高效开采低渗透油藏具有重要的理论和实际指导意义。
[Abstract]:Low permeability oil and gas reservoirs are widely distributed in China and have great resource potential. However, due to its special nonlinear percolation characteristics, the development of low permeability reservoir fluid is difficult and the well production is low. In view of the inherent advantages of horizontal well development, the use of horizontal wells to develop low permeability reservoirs has been more and more widely used in practical production. However, due to the influence of bottom water or edge water, water cut rises after production for a period of time, and water coning is formed, which affects the development effect of horizontal well. In this paper, for the segmental completion of horizontal wells in low permeability reservoirs, the method of segmented completion with variable blind sieve ratio is considered, which is developed from two aspects: the percolation theory of horizontal wells in low permeability reservoirs and the optimization theory of piecewise completion. Mainly completed the following work: 1) considering the starting pressure gradient, based on the idea of micro-element convergence, using the principle of superposition of potential and the principle of mirroring reflection, the low permeability closed reservoirs were established respectively. The model of segmented completion percolation in low permeability bottom water reservoir and low permeability edge water reservoir. (2) the method of segmented completion with blind tube is adopted. The blind tube and production horizontal section are arranged in horizontal wellbore spaced, starting from the basic theorems of percolation mechanics and fluid mechanics. In this paper, a pressure drop calculation model for horizontal wells with two kinds of completion methods, open hole completion and perforating completion, is established. The coupled connection equation is used to calculate the pressure drop in horizontal wells. The coupling models of 6 horizontal wells in low permeability reservoirs with three different boundary conditions under two completion modes are established respectively. By using the example data, the factors affecting productivity of the coupling model are analyzed. The results show that the productivity of horizontal wells in low permeability reservoirs decreases with the increase of starting pressure gradient, and increases with the increase of reservoir thickness. However, the increase tends to be more moderate, which indicates that the horizontal well has a limited ability to develop and improve production in a thicker low permeability reservoir. 4) the horizontal well output is taken as the objective function. Taking the length and the position of the center of the production horizontal well section as the optimization variables, six segmented completion optimization models for horizontal wells in low permeability reservoirs with three different boundary conditions under two completion modes were established. The genetic algorithm is used to develop the numerical simulation software to solve the problem, and the optimal segmentation schemes under different segmentation modes are given respectively. Finally, the sensitivity of the factors affecting the productivity of the optimization model is analyzed by designing the opening degree, the number of sections and combining with the actual oilfield data. The results show that the more horizontal wellbore sections for low permeability closed reservoirs, the larger the output, but with the increase of the number of horizontal sections, the increase of production rate tends to be flat. For low permeability bottom water reservoir and edge water reservoir, the output increases gradually with the increase of horizontal wellbore segment number, but the increase range is small, so the influence of horizontal wellbore segment number on the production of low permeability bottom water reservoir and edge water reservoir is weak. The theory of segmented completion optimization for horizontal wells in low permeability reservoirs established in this paper provides an important theoretical support for the production of low permeability reservoirs by using the method of segmented completion, and has important theoretical and practical significance for the efficient production of low permeability reservoirs.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE312;TE257

【相似文献】