Research Of Theory And Application On Evaluating Pressure Of Horizontal Well Completion

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.