射孔产能

Copyright 2012, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Heavy Oil Conference Canada held in Calgary, Alberta, Canada, 12 –14 June 2012. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
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SPE 157735
Introduction Production profile nonuniformity is one of the main problems in reservoir development with horizontal wells. In the 1990s, Landman and Goldthorpe1, Marett and Landman2, and Asheim and Oudeman3 investigated the effect of perforation density on the inflow perforamance of horizontal wells and proposed variable-density perforation schemes to control production profile. On this basis, other researchers4-8 have developed different perforation optimization models by applying different optimization agrithoms in the recent years. However, these studies mainly concentrate on homogeneous reservoirs and the study on heterogeneous reservoirs is rare. Starting with this motivating observation, we have accomplished two objectives in this work. First, based on an improved evaluation approach of permeability heterogeneity, a reservoir/wellore coupling model of perforated horizontal wells in heterogeneous, anisotropic parallelepiped reservoirs is presented by source function method. Then, a perforation density optimization method aiming at ideal production profile is proposed. Finally, an example optimization is presented and pressure regulating range of perforations and profile regulating effect are analyzed. This study provides a theoretical basis for the design of perforated completion for horizontal wells in heterogeneous, anisotropic reservoirs. Permeability Heterogeneity Evaluation Reservoir permeability is a regionalized variable, which has both random and structural characteristics. Duilofsky9 presented a s-k* approach which approximates permeability heterogeneity in terms of a constant background permeability k={kx, ky, kz} which captures global effects and an effective skin s which captures near-well effects. However, in the derivation of the effective skin s, Duilofsky ignored the permeability anisotropy which affects both the inflow behavior and the near-well pressure drawdown, resulting in reduced accuracy of the approximation approach. Hence, it is necessary to establish an effective near-well skin model in anisotropic reservoirs to improve the s-k* approach. Assume that the cross section of the heterogeneity affected near-well region perpendicular to the well mimics the pressure isobar10 as shown in Fig.1. Perform the following coordinate transformation to change the real anisotropic system to an equivalent isotropic system.
Abstract Horizontal wells which are characterized by large drainage area, small pressure drawdown and high production rate are more influenced by reservoir heterogeneity and wellbore pressure loss than vertical wells. These factors may lead to unequilibrium development and premature water breakthrough, resulting in shortened production period, reduced production and ultimate recovery. Perforated completion is a widely used completion technology of horizontal wells. As the only flow channel between the formation and the wellbore, perforation plays an important role on the inflow performance. This paper aims to develop a perforation optimization method for regulating production profile of horizontal wells in heterogeneous reservoirs. Based on an improved evaluation approach of permeability heterogeneity, a reservoir/wellore coupling model of perforated horizontal wells in heterogeneous, anisotropic parallelepiped reservoirs is presented, and hence a perforation density optimization method aiming at regulating production profile is proposed. The example optimization shows that, the lower perforation density has a wider pressure regulating range. With the increase of perforation length, both the converged pressure drop and pressure regulating range decrease. To obtain an ideal production profile, the perforation density in low-permeability region should be higher than that in high-permeability region. The stronger the near-well permeability variability, the greater the density range and the proportion of low density are. The smaller the density, the greater the impact of rounding error is, and hence the less satisfactory the regulating effect is. This study provides a theoretical basis for the perforated completion design of horizontal wells in heterogeneous, anisotropic reservoirs.