Research and Application of Cold Productivity Formula of Horizontal Well in the Power-Law Fluid Heavy Oil Reservoir

Considering the rheological properties of fluid, reservoir heterogeneity, and eccentricity factor, the productivity formula of horizontal well for the power-law fluid heavy oil reservoir is derived by transforming the three-dimensional seepage problem into a two-dimensional seepage problem. The heavy oil production calculated by this formula is in good agreement with the actual production in the offshore oil field. Then, the influencing factors of production are analyzed, and the results show that the power-law index has the greatest influence on production. When the power-law index is less than 0.8, the production increases slowly with the power-law index and when it is greater than 0.8, the production increases faster. The power-law index has a greater impact on production for higher production pressure differential and longer horizontal well. Anisotropy has significant influence on the production. When the value of Kh/Kv is less than 10, the production decreases rapidly with the Kh/Kv; after the value of Kh/Kv is greater than 10, the production decreases slower. Eccentricity has trivial impact on the production.

Isoparametric Element Analysis of Two-Dimensional Unsaturated Transient Seepage

A FEM for unsaturated transient seepage is established by using a quadrilateral isoparametric element, considering the fact that the main permeability does not coincide with the axis situation. It creates a function by using the element’s node hydraulic head and shape function instead of the real head in the Richard seepage control equation. With the help of the Galerkin weighted residual method, a FEM equation is given for analyzing 2-dimensional transient seepage problem. Further, based on the Jacobi matrix and Gauss numerical integral, it determines the elements of stiffness and capacitance matrices. This FEM equation considers not only the anisotropic of soil but also the uncoincidence between permeability and the axis. It is a common form of transient seepage. In the end, two examples illustrate the node accuracy of the quadrilateral element and the correctness of this FEM equation.

Seepage Analysis for Construction, with Applications to Some Projects in Hong Kong

Deep excavations are intensively carried out in many cities in China and other countries. One of the major loadings in such construction work is the water pressure, and great effort is required to assess the seepage problem and the corresponding water pressure on the retaining wall for a good design and construction. Different methods used for the seepage analysis are discussed in this paper through a series of projects in Hong Kong. Some interesting phenomena from the seepage analysis will also be discussed. Two large scale seepage field tests in Hong Kong are also used for the illustration of the back analysis in seepage problems which are seldom carried out. The comparative studies demonstrate that a realistic seepage analysis is very important for deep excavation works, but it was not seriously considered in the past.

Seepage Analysis in Short Embankments Using Developing a Metaheuristic Method Based on Governing Equations

Seepage is one of the most challenging issues in some procedures such as design, construction, and operation of embankment or earth fill dams. The purpose of this research is to develop a new solution based on governing equations to solve the seepage problem in an effective way. Therefore, by implementing the equations in the programming environment, more than 24,000 models were designed to be applicable to different conditions. Input data included different parameters such as slopes in upstream and downstream, embankment width, soil permeability coefficient, height, and freeboard. With the use of this big data, a new process was developed to provide simple mathematical models for the seepage rate analysis. The study first used intelligent models to simulate the seepage behavior. Finally, the accuracy of the models was optimized using a new metaheuristic algorithm. This led to the ultimate flexibility of the final model presented as a new solution capable of evaluating different conditions. Finally, using the best model, new mathematical relationships were developed based on this methodology. This new solution can be used as a proper alternative to the governing equations of seepage rate estimation. Another advantage of the proposed model is its high flexibility that can be well applied to engineering design in this field, which was not possible using the initial equations.

Effect of Presence of Single Cavity Upstream Side of Sheet Pile Wall on Steady Time and Quantity of Seepage

When the sheet pile is used as the reservoir wall or retains the action of saturated fills and cuts for construction works, it will be certain that the seepage occurs from the back side (retained side) to the working place (opposite side). Often, the rate of seepage and its quantity in homogenous strata depends mainly on the permeability of soil. However, the presence of cavity certainly has a direct impact on trend, steady time, and the quantity of seepage. The present study considered a preliminary attempt to measure this impact through physical model. Eighteen model tests are conducted to study the effect of different locations and diameters (size) of single cavity on the seepage problem when it is presented at upstream side (back side) of the sheet pile wall. Period of completion every model test ranged from four to seven days. The start time of seepage when the water began to flow from the downstream side (working place) ranged between 13min and 26min, which depended on the location of cavity and its size. However, the results show that the quantities of seepage generally increase with the smallest size of a cavity and with the farthest horizontal distance from the sheet pile. The maximum quantity has been recorded when the cavity is located at the same level of sheet pile end.