【作者】 王磊；

【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】 油田精细开发面临一系列新问题,如大厚油层中垂向渗透率等参数的测量,分层注水井的流量调配及考虑温度的气井压力解释等。这些问题中均涉及到多层油藏渗流规律这一共性问题。为此本文将不同渗流参数及热力学参数油藏视为多层,开展多层渗流基础方法研究。作者在油田进行多次现场试验,建立了符合油田实际的物理模型和数学模型,解决了问题并将这一研究成果应用到油田精细开发中。为解决大厚油层的垂向渗透率问题,本文首先从渗流力学基本方程出发,给出了考虑垂向渗流的单层油藏井底压力解析解,绘制了双对数图版并给出了相应的压力解释方法。考虑垂向流动的多层油藏和单层油藏的渗流规律具有一定的相似性,在建立多层油藏物理模型时,认为除了各层内流体的径向流动和垂向流动外,在两层交界面上还有层间越流,且相邻两层在交界面上的压力相等,垂直方向的渗流速度也相等。流体均通过第一层的射开段流入井筒,其它层与井筒不连通。通过定义一系列无量纲参数,将各层渗流方程和定解条件转换为无量纲形式,并在拉普拉斯空间上使用分离变量法联立求解各层的渗流方程,在求出井底压力表达式后通过拉普拉斯数值反演得到实空间上的井底压力表达式,根据各层的井底压力表达式画出双对数图版,供试井分析使用。双对数图版的形态由定义的无量纲参数决定,通过调整这些参数,使理论压力曲线与实测压力曲线吻合,即可得到真实的地层渗透率、井储系数和表皮系数。本文还研究了垂向渗透率测试的测试工艺并进行现场试验,这在国内尚属首例。在研究注水井流量调配过程中的流体流动规律时,将注水井中的流动分为井筒管流、配水器节流和地层渗流三个过程,分别研究了它们的流动规律和三者的耦合流动,并考虑了周围井网的影响。在井筒管流的研究中,通过伯努利方程,建立了井口压力和各层配水器嘴前压力的关系式;在配水器节流的研究中,使用数值方法模拟了配水器中的流动,发现水嘴的总压损失和注入量的平方成正比;在地层渗流的研究中,计算了定流量注入的无限大地层中不考虑井筒半径的直井、考虑井筒半径的直井及垂直裂缝井的井底压力表达式。最后综合考虑三种流动,得出了各层注入量与井口压力及各层水嘴直径的关系式。在理论分析的基础上,给出了具体的流量调配方法——升压法。通过改变井口压力,分别测量改变前后的各层配水器嘴前压力和注入量就能计算出各层的吸水指数,根据吸水指数和各层计划注入量计算出合适的井口压力和各层水嘴直径。从节约成本的角度考虑,应使井口压力在满足计划注入量误差要求的情况下尽可能的小。气井井筒中的温度并不是常数,由于压力计一般不下到产气层,所以压力计处和产气层有温差,在进行试井分析时必须考虑由温差引起的附加压力。本文在建立气井热量传递模型时根据热力学参数和物理性质的不同,将地层分为多层,并忽略地层中的垂向热传导,认为只有水平方向的热传导,同时忽略井筒中的垂向热传导,认为只有垂向的热对流。将气井中的热量传递分为三个部分,分别为井筒内的一维热对流,热表皮区的热量传递(包括环空的对流和辐射,水泥环的热传导)和地层中的水平方向热传导。分别建立井筒中的对流方程和地层中的热传导方程并用综合热传导系数联系地层温度和井筒温度,最后求解出井筒中的温度分布表达式和地层温度分布表达式。在建立模型时认为产气层厚度很小,与其它层相比厚度可以忽略,从而产气层内的温度为常数。使用拟压力法得出产气层的井底拟压力,并考虑温度产生的附加拟压力最终得到压力计处的拟压力表达式。根据此表达式画出考虑温度的气井井底压力理论曲线并进行了分析。更多还原

【Abstract】 A series of new problems are essentially needed to be solved at fine development of oil field, such as measurements of vertical permeability and other formation parameters at different depths of a thick oil layer, the method of separate layer water injection and the pressure interpretation method of gas well considering temperature effect. These problems are all related to the law of fluid flow in multi-layer reservoirs. The heterogeneous reservoir is divided into layers with different formation parameters and thermodynamic parameters in this paper, and the law of fluid flow in these layers is studied. Lots of tests are carried out at oil fields, and physical and mathematical models are built up. The results have been applied to fine development of oil field after the problems are solved.The analytical pressure formula of a single-layer reservoir considering vertical flow is first given to solve the problem of measurements of vertical permeability of a thick oil layer on the basis of basic equation of fluid mechanics in porous media. The corresponding log-log type curves are drawn and the pressure interpretation method is built up. The law of fluid flow in multi-layer reservoir has some extent similarity with that in single-layer reservoir. Cross flow between neighboring layers, horizontal and vertical flow in layers are considered on the assumption of that pressure and vertical flow of the neighboring layers are equal, and fluids only flows through perforations of top layer in wellbore,which means fluid is not permitted to flow into other layers. Seepage equations and corresponding definite conditions are transformed to dimensionless forms by defining some dimensionless parameters. They are solved by using the method of separation of variables in the Laplace space and then solutions in the real space are given by Laplace inversion. Log-log type curves are drawn for pressure interpretations and the profiles of the curves are controlled by the dimensionless parameters. The test technology of vertical permeability is studied and some field tests are carried out, that is the first try at China.The fluid flow at separate layer water injection can be considered as three parts, which are the pipe flow in the well bore, throttle flow in the water distributor and the seepage in the reservoir. In the study of the pipe flow, the relationship between the wellhead pressure and the wellbore pressures of the layers is built up through the Bernoulli equation. In the study of throttle flow, the flow in the water distributor is simulated by numerical methods and it is found that the total pressure loss is proportional to the square of the flow rate into the water distributor. In the study of the seepage in the reservoir, the wellbore pressure formulas of the vertical well and the vertically fractured well are derived with infinite boundary and constant flow conditions. Considering all the three types of flows, the relationship between wellhead pressure and tap diameters of water distributors of different layers is proposed. Finally an effective method named pressure rise method is given to adjust flow rates of the layers. When changing the wellhead pressure, flow rates and pressures of the layers can be measured. On the basis of the measurement the water injection indexes are calculated. Then proper wellhead pressure and tap diameters will be calculated through water injection indexes and flow rates of the layers. The wellhead pressure should be as small as possible when the flow rate error limits are satisfied in order to reduce the costs.The temperature in gas well bore is not constant and the position of the pressure gauge is usually higher than the one of the gas production layer. As a result temperature difference between them causes additional pressure. This effect should be considered in pressure interpretation. The formation is divided into many layers according to thermodynamic parameters and single layer has uniform thermodynamic parameters. The vertical heat conductivity in the layers is ignored and only the horizontal heat conductivity is considered. The vertical heat conductivity in the well bore is also ignored and only the vertical heat convection is taken into account. The heat transfer of gas well can be considered as three parts, the vertical heat convection in the well bore, the horizontal heat conductivity between the well bore and the formation and the horizontal heat conductivity in the formation. The temperature distribution can be calculated on the basis of the heat convection equation in the well bore, the heat conductivity equation in the formation and the integrated heat conductivity coefficient. The temperature of the gas producing layer is considered as constant because the thickness is too small compared with other layers. Pseudo pressure is used to obtain the well bore pressure formula of the gas well, and the final result is corrected by the additional pressure. Finally the log-log type curves are drawn and the pressure data is interpreted.更多还原