Conventional horizontal well transient response models are generally based on the line source approximation of the partially penetrating vertical fracture solution[1].These models have three major limitations:wellbore pressure is computed at a finite radius outside the source; it is impossible to compute wellbore pressure within the source,it is difficult to conduct a realistic comparison between horizontal well and vertical fracture productivities, because wellbore pressures are not computed at the same point, andthe line source approximation may not be adequate for reservoirs with thin pay zones. This work attempts to overcome these limitations by developing a more flexible analytical solution using the solid bar approximation. A technique that permits the conversion of the pressure response of any horizontal well system into a physically equivalent vertical fracture response is also presented. A new type curve solution is developed for a horizontal well producing from a solid bar source in an infinite-acting reservoir by means of Newman's product solution[2]. Analysis of computed wellbore pressures reveals that error ranging from 5 to 20% was introduced by the line source assumption depending on the value of dimensionless radius (rwD). Computations show that for rwD = 10–4 the transient response of a horizontal well is identical to that of a partially penetrating vertical fracture system, and for rwD = 0.01 the transient response of a horizontal well is indistinguishable from that of a horizontal fracture system. Type-curve plots for the ranges 0.01 = dimensionless length (LD) = 10, and 10–4 =rwD = 1.0 are presented. A dimensionless rate function (ß-function) is introduced to convert the transient-response of a horizontal well into an equivalent vertical fracture response. A step-wise algorithm for the computation ofß-function is developed using Duhamel's principle. This provides an easier way of representing horizontal wells in numerical reservoir simulation without the rigor of employing complex formulations for the computation of effective well block radius. Introduction Conventional models for horizontal well test analysis were mostly developed during the 1980s. The rapid increase in the applications of horizontal-well-technology during this period led to a sudden need for the development of analytical models capable of evaluating the performance of horizontal wells. Ramey and Clonts[3] developed one of the earliest analytical solutions for horizontal well test analysis based on the line source approximation of the partially penetrating vertical fracture solution. Conventional models [4–16] assume that a horizontal well may be viewed as a well producing from a line source in an infinite-acting reservoir system. These models have three major limitations:wellbore pressure is computed at a finite radius outside the source; it is impossible to compute wellbore pressure within the source,it is difficult to conduct a realistic comparison between horizontal well and vertical fracture productivities, because, wellbore pressures are not computed at the same point,the line source approximation may not be adequate for reservoirs with thin pay zones. The increased complexity in the configuration of horizontal well completions and applications towards the end of the 1980s made us question the validity of the horizontal well models and the well-test concepts adopted from vertical fracture analogies. In the beginning of the 1990s a new wave of developing horizontal-well solutions[17–27] under more realistic conditions emerged. As a result, some contemporary models were developed to eliminate the limitations of the earlier horizontal well models. However, the basic assumptions and methodology employed in the development of these new set of solutions have remained relatively the same as those of the earlier models. Ozkan[28] presented one of the most compelling arguments for the fact that horizontal wells deserve genuine models and concepts that are robust enough to meet the increasingly challenging task of accurately evaluating horizontal well performance. Ozkan's work presented a critique of the conventional and contemporary horizontal-well-test analysis procedures with the aim of establishing a set of conditions when the conventional models will not be adequate and the margin of error associated with these situations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.