【作者】 卫五洲；

【导师】 卢德唐；

【作者基本信息】 中国科学技术大学 ， 流体力学， 2008， 博士

【摘要】 随着低渗油藏不断发现,复杂井型技术被广泛用于石油勘探开发之中,例如过去的三十年快速发展水平井技术。不同于垂直井,水平井不同完井类型的压力评价理论要复杂的多,针对水平井射孔完井和砾石充填完井两种,本文从以下几个方面对此进行了研究。1、线源解。水平井射孔完井后,地层中的流体在多孔介质中的流动符合达西定律,本文将射孔后地层和井筒之间的流动通道考虑成线源,根据格林函数和乘积原理用源汇法推导出线源的瞬态压力乘积解,主要研究了螺旋射孔格式下相位角为90°射孔完井地层中的流动情况,得到各点的压力变化和任意时刻的压力分布,采用的方法是首先把孔眼分为Ⅰ类和Ⅱ类,根据两类孔眼形成流动通道的不同,得到在多种边界条件下的两类孔眼的线源解。2、并行计算。水平井的长度一般10~3米量级,因而沿着井筒的孔眼数则有10~1量级,虽然每个孔眼对油藏都有“扰动”,但是孔眼与孔眼之间没有通讯,是相互独立的,而且对于油藏中的各点来说,孔眼的影响体现在地层压力的变化,这种特点适合采用并行计算,对于这么多孔眼的计算也只能采用并行计算技术,本文采用结构化网格技术实现了在大型并行机群(KD-50-Ⅰ)计算水平井射孔后的地层压力变化和分布,以及速度的变化和分布。3、算法优化。为了提高并行计算的效率,在不影响计算准确度的情况下,变化网格划分方法,实现算法的优化。采用的方法在对数空间下对油藏区域进行网格划分,然后在实空间下进行了迭代,同样在时间维度上也可以用这种方法进行划分,依据是油藏中距离井筒远的地方,孔眼流动对地层的影响很小,同时随着时间的增加,油藏中的流动趋于稳定,也没有必要在时间上进行相同的迭代,这样就大大减少了循环的次数,优化了算法。4、径向流和产能预测。本文根据地层中速度的分布情况,定义径向流的区域,认为在该区域可以用理想的裸眼完井模型计算底地压力分布和变化,在径向流区域和射孔影响区域的交界面存在着压差认为是由水平井射孔引起的附加压降也就是表皮因子,因而可以准确地预测油气井射孔完井的油气产能,同时利用现代的录井技术,根据本文的模型可以实时预测油气产能。5、砾石充填完井。本文的最后,提出水平井砾石充填完井方式的压力计算思路,将油藏划分为三个区域:径向流区、射孔区和砾石充填区,分别给出各流动区的计算模型原理,在边界条件上耦合三种区域的流动,达到地层中流体流动的连续。通过上述理论推导和数值计算模拟,我们研究了水平井射孔完井后地层中液体流动的特点,提出了水平井砾石充填完井计算的物理数学模型,为实现对地层的数值模拟计算提供了思路。更多还原

【Abstract】 With many low permeability reservoirs be found, non-conventional wells is widely used in oil exploration and development, such as the rapid development of horizontal well technologies in the past 30 years. The theory of pressure evaluation on different type completion of horizontal well is much more complicated than the vertical wells, and for perforated completion and gravel packed completion of horizontal wells, the following aspects were studied in this paper.1. Solution of Linearity Source. After horizontal perforated completion, the flowing of fluid in porous media fits with the flow of Darcy’s law. In this paper the transient pressure analytic model was deserved when the flowing channels, which were produced by perforation between reservoirs and wellbore, were considered as linearity source according to Green’s function and product method, and the phase angle is 90 degree with helix-perforating is the main subject in this research. First all the perforations were divided two types: style I and style II then the transient pressure expression of every style is deserved with all kinds of boundary conditions, so transformation and distributing of the pressure and velocity in the formation is known.2. Parallel Computation. The length of horizontal is about several thousand kilometers, and the number of perforations can be reached several decades thousand. All the perforations are isolated points and have no exchange of information with each other, further more the effect of the perforating of horizontal well can be added. According to that, in this paper the parallel computation was used in the computing the pressure and velocity of the formation at every point and time, and good results were got at high-performance parallel computers KD-50- I3. Algorithm Optimization. In order to improve the efficiency of parallel computing, the optimization of the parallel algorithm was conducted in the case of the error could be omitted. The method was used in this paper is that the reservoir area was meshed in the logarithm space, and then was iterative in real space, so the circulations was decreasing very mach. The reasons are that the effect of the perforating is faintness because of the far distance from the wellbore and long time from the start.4. Radial Flow and Productivity Forecast. In this paper, according to the distribution of the velocity in the formation, the scope of radial flow region was defined, and the transformation and distributing of the pressure were computed with the open completion model without damage. The pressure drop, which was considered as the cause of the skin factor, can be computing at the intersection surface between the radial flow regions and perforating region, so the productivity of the perforated horizontal can be forecasted. At the same, the performance can also be evaluated real time by the advanced log well technologies.5. Gravel Packed Completion. At the end of this paper, the idea of calculating the pressure of horizontal well with gravel packed completions was submitted, and the reservoir was divided three parts such as radial flow regions, perforation region and gravel packed region. The principle of each model was given, and continuity of the flow was ensured by the coupling the boundary condition.Through this theoretical analysis and numerical simulation, we have studied flowing characteristics of liquid in the formation of horizontal wells perforated completion, and the physical computing model of gravel packed completion of horizontal wells is proposed, so the idea of numerical simulation to compute the formation of gravel packed completion of horizontal wells is submitted.更多还原