二元复合驱油藏数值试井技术研究与应用

本文利用流线数值试井方法,研究了复合驱油藏试井模型,得到了压力响应特征。应用实践表明,二元复合驱流线数值试井技术可以考虑复合驱过程中主要的驱油机理、多相流、油藏非均质性、多井影响等复杂因素的影响,解释结果准确可靠。     

生产测井资料的一种新用法

为了求解抽油井中的地层边界压力和泵效。对生产测井得到的流量曲线进行了分析。结合井底压力测量值得到油层边界供液压力。实际应用表明这是一种可行的方法。     

间歇调流控水采油技术探讨

在底水油藏开发中后期,底水的突破是不可避免的。由于水平井段的储层非均质性,以及流入井筒流体流动剖面的不均匀性,水体优先突破的部位具有选择性。非均质储层中高渗带和均质储层的井底段更容易造成过早的水体突破,严重时甚至能引起局部井段水淹。讨论了间歇调流控水采油技术的原理方法及现场应用,并分析认为在水平井产能越大,井段流入剖面越不均匀的水平井中,调流控水采油效果越好。     

FZ1井区SAGD开发动态调控技术优化研究

风城油田超稠油油藏具有埋藏浅、非均质性强、隔夹层发育等特点,目前已进入高产稳产阶段,为指导生产,分析了注采情况,结合温度压力联动变化关系,对现有调控技术进行了优化。通过分析压力变化可以了解单井注采情况;对于多井蒸汽腔连通区域可使用系统采注比分析;井底操作压力,高压增能扩腔、中压节汽控温、低压补汽保腔。     

一维径向单相流油藏数值模拟方法

研究单井动态问题时,通常将井底附近的流动看做一维径向流动,此时,最经典的特点是沿着井轴压力呈圆形分布,且井底周围的压力变化快,而远离井底附近的压力变化小。因此,需要采取不等距网格来模拟单井的问题。该研究主要针对一维径向单相流油藏数值模拟方法,得出典型的一维径向单向流的解来刻画油藏特征。     

北部过渡带周期注水的应用与效果分析

周期注水是通过不断在油层中人为的建立不稳定的压力场来扰动油层,使得同一油层内油水在高低渗透层之间相互交渗,提高非均质性储层的驱油效率的一种技术。针对北部过渡带地区油层非均质性比较严重,原油物性差、粘度高的情况,结合多年来在过渡带周期注水实验及效果,对北部过渡带进行周期注水的应用,并取得较好效果。     

特低渗油藏产能预测及主要影响因素分析

研究表明,特低渗油藏的产能预测,必须考虑启动压力梯度、渗透率变异系数及地层原油脱气对产能的影响;结合前人对低渗储层渗流特性的研究~([3-5]),并结合实例对主要影响因素进行了分析。结果表明,产能随启动压力梯度和渗透率变异系数的增大而减小,启动压力梯度的大小并不影响IPR曲线的形状,而是使曲线发生平移;渗透率变异系数的增大,使IPR曲线变得更加弯曲;井底流压相同,启动压力梯度及渗透率变异系数越大,产能越低;随井底流压降低,地层原油脱气形成油、气两相流,降低了原油的流动效率,产量出现最大值后降低。     

低渗透压敏油藏产能特征分析及生产参数确定

实验表明低渗透油藏渗流存在非达西渗流,即存在启动压力梯度!同时还有些低渗油藏存在压敏效应．所以在低渗油藏的开发中,启动压力和岩石的压敏效应必须考虑。同时常规的达西渗流下的产量公式也已经不适合低渗油藏的开发：结合考虑压力敏感和启动压力梯度的低渗油藏产能公式进行产能特征分析,进而确定合理的生产压差和极限井距。     

注采平衡图版在葡萄花油田的应用

注采平衡图版是通过注水油藏物质平衡原理及油水井压力剖面平衡式推导出来的注采平衡关系图版,由不同井底流压下的日产液量与地层压力关系曲线与不同注水压力下的日注水量与地层压力关系曲线交绘组成,图版上每一个交点都表明日产液量、日注水量、油井流压、注入压力和地层压力之间的平衡关系。并由此判断目前压力水平是否达到注采平衡,确定合理提液方式,指导注水油藏开发调整。     

孤东油田七区西北部特高含水期剩余油挖潜技术

孤东油田七区西北部上馆陶组属内陆河流相沉积的非均质多层砂岩亲水稠油油藏,油水粘度比大、非均质性严重,中低含水期含水上升快,水淹不均匀,因此特高含水期仍有大量剩余油分布,针对剩余油分布的各种形态,通过细分流动单元、简化层系、补孔扩射、优化注水压力、堵调结合、防砂扶井六项挖潜技术实施剩余油挖潜,改善油藏水驱效果提高采收率,在现场应用取得了显著效果。     

A useful approach to sensitivity and predictability studies in geophysical fluid dynamics: conditional non-linear optimal perturbation

In atmospheric and oceanic studies, it is important to investigate the uncertainty of model solutions. The conditional non-linear optimal perturbation (CNOP) method is useful for addressing the uncertainty. This paper reviews the development of the CNOP method and its computational aspects in recent years. Specifically, the CNOP method was first proposed to investigate the effects of the optimal initial perturbation on atmosphere and ocean model results. Then, it was extended to explore the influences of the optimal parameter perturbation, model tendency perturbation and boundary condition perturbation. To obtain solutions to these optimal perturbations, four kinds of optimization approaches were developed: the adjoint-based method, the adjoint-free method, the intelligent optimization method and the unconstrained optimization method. We illustrate the calculation process of each method and its advantages and disadvantages. Then, taking the Zebiak–Cane model as an example, we compare the CNOPs related to initial conditions (CNOP-Is) calculated by the above four methods. It was found that the dominant structures of the CNOP-Is for different methods are similar, although some differences in details exist. Finally, we discuss the necessity and possible direction for designing a more effective optimization approach related to the CNOP in the future.     

On a Method of Solving Sensitive Boundary Value Problems

Nonlinear two-point boundary value problems have always been difficult to solve. The difficulty is compounded if the problem tends to be inherently unstable. This paper describes an algorithm for solving such sensitive boundary value problems. The procedure is based on a computational method for finding the general solution of systems of ordinary differential equations used in conjunction with the multi-point quasilinearization method of Miele. The method is demonstrated by solving Troesch's problem and a singular perturbation problem.     

边界元法中角点问题的一种计算方法

在分析边界元法中多种角点处理方法的基础上,提出了一种新的方法-单角点法.该方法在继承双角点与二重节点法优点的基础上,不仅提高了解的精度且有效解决了边界变形的问题.     

轴对称有无相变导热问题的双倒易边界元模拟

发展了轴对称问题的双倒易边界元方法.引入一个新的f函数，解决了以前使用的f 函数在对称轴上存在奇异性的问题，并成功地计算了一些非定常导热与带有运动边界条件的相变传热问题.     

Asymptotic stability of a viscoelastic elliptic shaft

A finite viscoelastic shaft whose model is based on the spring and dash-pot (Kelvin element) is asymptotically stable as long as its angular speed is less than or equal to the square root of the least eigenvalue of the system. We construct numerically the least eigenvalue by using an iteration method where a definite integral is evaluated by the GAUSQZ method. With this construction, we show that a viscoelastic elliptic shaped shaft with both ends pinned is more stable than the tapered shaft with both ends pinned, or with one end built in and the other end free.     

Numerical estimation of two convective boundary conditions of a two-dimensional rectangular fin

A simultaneous estimation of two convective boundary conditions problem of a two-dimensional rectangular fin is proposed by numerical approach. The aim is to estimate the evolution of the distributions of the unknown heat transfer coefficients from the transient temperature histories taken with several sensors inside a two-dimensional fin. The estimation algorithm of this inverse heat conduction problem is based on the iterative regularization method and on the conjugate gradient method. An optimal choice of the vector of the descent parameters is used in this study and shows an increase in the convergence rate. The effects of some parameters (sensor number, position, measurement errors) on the inverse solutions are discussed.     

Investigation of a novel perforation technique in petroleum wells—perforation by drilling

The objective of perforating the petroleum wells is to maximize well productivity. A good connectivity between the wellbore and formation can lead up to achieve that goal. However, the conventional method of perforation, which basically involves the use of explosive charges, rarely meets the expected well productivity. It is mainly because of the formation of a region of reduced permeability around the perforation tunnel. To offset such and several other shortcomings of present practices, a new technique is required, the highlight of this paper. Described as the ‘perforation by drilling’ (PD), this new technique is examined and compared for its performance with that of another technique, ‘Perforation by Shooting’ (PS). For this, the experimental and numerical results of the PS technique on cylindrical sand samples of varying amounts of strength and porosity are studied. Moreover, in order to achieve a so-called ‘perfect perforation’, results are compared with the ‘Casting technique’. Three different samples were selected for the measurement of fluid flow rate and differential pressure across the perforation using a ‘geotechnical digital system’ (GDS), which is a triaxial testing device. Profiles such as fluid flow rate with a change in differential pressure and pressure build-up data with time, signify that the PD technique can achieve maximum wellbore productivity when compared to the PS technique. Results also indicate that at a 100 kPa differential pressure, the PS, PD and Casting techniques can achieve 0.20, 0.65 and 1.00 mL/s fluid flow rates respectively across a sample. The paper also implements a 1-D time dependent porous media flow model to simulate flow across the perforated cylindrical samples created by the PS, PD and Casting techniques. Results show a good consistency between the experimental and numerical approaches.     

横观各向同性土体二维固结孔压影响范围分析

在先假定孔压分布边界条件为一待定常数的基础上,求解了条形荷载作用下二维横观各向同性固结微分方程,得出了孔压为平面坐标和时间函数的表达式,再通过假定该待定常数为一系列具体数值时得出的固结解的结果,用反分析的方法得出孔压沿水平向消散为零的范围。得到的结论对工程实践和进一步的理论分析都具有一定的意义。     

Effect of seasonality on the dynamical behavior of an ecological system with impulsive control strategy

In this paper, on the basis of the theories and methods of ecology and ordinary differential equation, an ecological model consisting of two preys and one predator with impulsive control strategy and seasonal effects is established. Conditions which guarantee the global asymptotical stability of the prey-eradication periodic solution are obtained using the theory of impulsive equations, small amplitude perturbation skills, and comparison techniques. Further, the influences of the impulsive perturbation and seasonal effects on the inherent oscillation are studied numerically. These show to be consistent with the theoretical analysis and rich complex population dynamics, such as species extinction and permanence. Moreover, the population dynamical behavior of the model is demonstrated by the computed largest Lyapunov exponent. By investigating the strange attractors through their computed Fourier spectra, we know that seasonality has a profound effect on the population dynamical behavior. All these results are expected to be of use in the study of dynamic complexity of ecosystems.     

Interaction between cells in dielectrophoresis and electrorotation experiments

Progress in microelectrode-based technologies has facilitated the development of sophisticated methods for manipulating and separating cells, bacteria, and other bioparticles. For many of these various applications, the theoretical modeling of the electrical response of compartmentalized particles to an external field is important. In this paper we address the analysis of the interaction between cells immersed in rf fields. We use an integral formulation of the problem derived from a consideration of the charge densities induced at the interfaces of the particle compartments. The numerical solution by a boundary element technique allows characterization of their dielectric properties. Experimental validation of this theoretical model is obtained by investigating two effects: (1) The influence that dipolar “pearl chaining” has on the dielectrophoretic behavior of human T lymphocytes and (2) the frequency variation of the spin and orbital torques of approaching insulinoma β-cells in a rotating field.