A new method for interpreting well-to-well interference tests and quantifying the magnitude of production impact: theory and applications in a multi-basin case study
Abstract: Interference tests are used in shale reservoirs to evaluate the strength of connectivity between wells. The results inform engineering decisions about well spacing. In this paper, we propose a new procedure for interpreting interference tests. We fit the initial interference response with the solution to the 1D diffusivity equation at an offset observation point. It is advantageous to use the initial interference response, rather than the subsequent trend, because the initial response is less affected by nonli… Show more
Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
Cited by 6 publications
References 31 publications
Quantifying the Effects of Interwell Communication Using Dynamic Fluid-in-Place Calculations
Summary Multifractured horizontal wells (MFHWs) completed in the same reservoir layer, or different reservoir layers, commonly experience interwell communication through hydraulic fractures. For example, after a well is placed on production, its production performance can be impacted by communication with an offsetting well placed on production after it. The degree of communication between wells is important to quantify for the purposes of well production forecasting, reserves estimation, completions, and well spacing design optimization. In this study, dynamic fluid-in-place calculations, performed using the impacted producing well rates and flowing pressures, are applied to quantify the effect of communication with an offset-producing well on the impacted well-contacted fluid-in-place estimates. Agarwal (2010) demonstrated that pressure transient analysis theory can be used to derive the volume of fluid in place contacted by a well (CFIP) over time during constant rate, transient production. The method was later extended to variable-rate/pressure scenarios. However, all previous applications of Agarwal’s method were for single, isolated wells and assumed single-phase flow of oil and gas. To evaluate the usefulness of the method for modern development scenarios, it is extended to allow for quantification of interwell communication during flowback, for which single-phase flow of water before the breakthrough of formation fluids may precede multiphase flow of formation and fracturing fluids, and for analysis of multiphase data. Analysis of flowback data enables early-time identification and quantification of interference effects. Multiple numerical simulation cases are generated to simulate different degrees of communication for the case of a two-phase flow of oil and water. Wells are assumed to be communicating through a hydraulic fracture with a specified transmissibility multiplier (Tmult) used to adjust the amount of interwell communication. Corrections for multiphase flow in the CFIP method are performed using two different methods—the total volumetric flow rate (combined phase) approach and the multiphase pseudovariable approach. The CFIP diagnostic plot (i.e., log-log plot of CFIP vs. material balance time) is applied to the impacted producing well to evaluate the CFIP trend before and after offset well production and the magnitude of CFIP change. The practical application of the method is demonstrated with field cases. From the simulation cases, it is observed that, after the offset well is placed on production, a reduction of CFIP for the impacted producing well occurs (rapidly decreasing at first and then stabilizing after a transition period) proportional to productivity index reduction. The loss in CFIP for the impacted producing well can be determined simply by estimating its CFIP immediately before and after offset well production. For high connectivity (Tmult> 0.25) scenarios, application of the combined phase approach resulted in estimates of the impacted well CFIP reduction of ~46–50%, whereas application of the modified pseudovariable approach resulted in estimates of ~49–51%. For the low connectivity case (Tmult = 0.001), these estimates were ~11% and ~9%, respectively, for the two approaches. Therefore, for the simulation cases studied herein, the two approaches agreed within acceptable error. Numerical simulation was also used to verify the absolute change in CFIP using these two approaches for correcting for multiphase flow. The practical application of the modified CFIP method was demonstrated using two field cases with early-time production. Both field cases demonstrated that changes in CFIP for the impacted well can be unambiguously interpreted. In the first field case corresponding to early-time production data (gas and water) associated with Well 23 of the SPE data repository, the reduction in CFIP of the impacted producing well was estimated to be ~37% using the combined phase approach. In the second field case, for which a producing well completed in a low-permeability gas condensate reservoir is impacted by placing multiple offset wells on production at the same time, the reduction in CFIP of the impacted well was estimated to be ~20% using the combined phase approach. In this study, we demonstrate for the first time that CFIP calculations can be applied to quantify interwell communication between two wells during flowback or early-time production when multiphase flow occurs in the reservoir.
Quantifying the Effects of Interwell Communication Using Dynamic Fluid-in-Place Calculations
Summary Multifractured horizontal wells (MFHWs) completed in the same reservoir layer, or different reservoir layers, commonly experience interwell communication through hydraulic fractures. For example, after a well is placed on production, its production performance can be impacted by communication with an offsetting well placed on production after it. The degree of communication between wells is important to quantify for the purposes of well production forecasting, reserves estimation, completions, and well spacing design optimization. In this study, dynamic fluid-in-place calculations, performed using the impacted producing well rates and flowing pressures, are applied to quantify the effect of communication with an offset-producing well on the impacted well-contacted fluid-in-place estimates. Agarwal (2010) demonstrated that pressure transient analysis theory can be used to derive the volume of fluid in place contacted by a well (CFIP) over time during constant rate, transient production. The method was later extended to variable-rate/pressure scenarios. However, all previous applications of Agarwal’s method were for single, isolated wells and assumed single-phase flow of oil and gas. To evaluate the usefulness of the method for modern development scenarios, it is extended to allow for quantification of interwell communication during flowback, for which single-phase flow of water before the breakthrough of formation fluids may precede multiphase flow of formation and fracturing fluids, and for analysis of multiphase data. Analysis of flowback data enables early-time identification and quantification of interference effects. Multiple numerical simulation cases are generated to simulate different degrees of communication for the case of a two-phase flow of oil and water. Wells are assumed to be communicating through a hydraulic fracture with a specified transmissibility multiplier (Tmult) used to adjust the amount of interwell communication. Corrections for multiphase flow in the CFIP method are performed using two different methods—the total volumetric flow rate (combined phase) approach and the multiphase pseudovariable approach. The CFIP diagnostic plot (i.e., log-log plot of CFIP vs. material balance time) is applied to the impacted producing well to evaluate the CFIP trend before and after offset well production and the magnitude of CFIP change. The practical application of the method is demonstrated with field cases. From the simulation cases, it is observed that, after the offset well is placed on production, a reduction of CFIP for the impacted producing well occurs (rapidly decreasing at first and then stabilizing after a transition period) proportional to productivity index reduction. The loss in CFIP for the impacted producing well can be determined simply by estimating its CFIP immediately before and after offset well production. For high connectivity (Tmult> 0.25) scenarios, application of the combined phase approach resulted in estimates of the impacted well CFIP reduction of ~46–50%, whereas application of the modified pseudovariable approach resulted in estimates of ~49–51%. For the low connectivity case (Tmult = 0.001), these estimates were ~11% and ~9%, respectively, for the two approaches. Therefore, for the simulation cases studied herein, the two approaches agreed within acceptable error. Numerical simulation was also used to verify the absolute change in CFIP using these two approaches for correcting for multiphase flow. The practical application of the modified CFIP method was demonstrated using two field cases with early-time production. Both field cases demonstrated that changes in CFIP for the impacted well can be unambiguously interpreted. In the first field case corresponding to early-time production data (gas and water) associated with Well 23 of the SPE data repository, the reduction in CFIP of the impacted producing well was estimated to be ~37% using the combined phase approach. In the second field case, for which a producing well completed in a low-permeability gas condensate reservoir is impacted by placing multiple offset wells on production at the same time, the reduction in CFIP of the impacted well was estimated to be ~20% using the combined phase approach. In this study, we demonstrate for the first time that CFIP calculations can be applied to quantify interwell communication between two wells during flowback or early-time production when multiphase flow occurs in the reservoir.
Modeling and Analysis of Pressure- and Rate-Transient Behavior of Interfering Horizontal Wells in Multi-Layer Unconventional Reservoirs
Multi-well systems are essential for unconventional asset development by optimizing the reservoir drainage, well productivity, and cumulative recovery to maximize the economics of the project. Although the underlying principles of infill drilling and multi-well production is the same as that for conventional reservoirs, in unconventional reservoirs, the contrast between the stimulated and unstimulated volumes (SRV and ORV, respectively) of the reservoir, differences in well completions and resulting SRV vs. ORV properties, asynchronous start of production, different production conditions, and unmatching schedules of production and shut-in periods further complicate the design (the spacing, completion, and production conditions) of the multi-well systems. Moreover, development decisions are usually made with uncertainties caused by the complexity of well-interferences in the existence of extreme reservoir heterogeneity. Therefore, to make multi-well unconventional reservoir development decisions, both the knowledge of the interwell reservoir characteristics and their effect on the multi-well productivity of the system must be known. These requirements call for models that are accurate and efficient for estimating reservoir and completion parameters by pressure- and rate-transient analysis (PTA and RTA, respectively) and capable of efficiently evaluating multiple development scenarios subject to the uncertainties of reservoir characteristics. We have developed robust semi-analytical models to analyze the performances of multi-well systems in single and multi-layer completion conditions in unconventional reservoirs. This paper discusses the diagnostic features of pressure- and rate-transient behaviors of multiple wells in single- and multi-layer unconventional-reservoir, delineates the sensitivities of well performances to well spacing, stimulation treatment, and production conditions of interfering wells, and demonstrates the application of the models to PTA and RTA of field cases. The PTA/RTA methodology presented in this work consists of obtaining initial estimates of the well completion and reservoir properties through diagnostic and straight-line analysis of specific flow regimes, guided by the multi-well solution, and refining the estimates by matching the transient well responses by the semi-analytical model. This methodology provides a remarkably efficient and reasonably accurate estimation of properties within the bounds of the system uncertainties.
Whispers from the Reservoir: Well Interference Testing Unlocks Insights for Optimal Well Spacing and Completions Design in a Delaware Basin Case Study
Optimizing well spacing in unconventional reservoirs employing multi-stage hydraulic fracturing remains a significant challenge. While overly close spacing incurs detrimental inter-well interference, excessive spacing leads to inefficient resource recovery. This study aims to present a workflow for pressure interference testing to optimize well spacing in unconventional reservoirs using early-time data. The proposed workflow integrates pressure interference testing with reservoir simulation and a real-world case study from the Delaware Basin, New Mexico. The case study focuses on three target reservoirs: Avalon, First Bone Spring Sand, and Second Bone Spring Limestone. To assess pressure communication and optimize well spacing, downhole pressure gauges were strategically deployed within each formation. This strategic placement enables the monitoring of pressure responses both during hydraulic fracturing and throughout production in each specific reservoir zone. Data analysis then evaluates the initial well spacing assumptions and identifies potential vertical and lateral communication between the zones. The Delaware Basin case study validates initial well spacing assumptions and provides early insights into reservoir connectivity. This information facilitates the optimization of completions design and well spacing. The study concludes that the pressure interference testing workflow offers a valuable tool for reservoir and completions engineers. Consequently, the workflow prevents loss of capital due to suboptimal design, ultimately leading to more efficient and cost-effective reservoir management. This paper presents a novel workflow that strengthens pressure interference testing by incorporating DQI (Devon Quantification of Interference) method. Additionally, this workflow transcends traditional pressure interference testing as it advocates for the integration of additional diagnostic techniques, such as fiber optics, offset pressure monitoring, and time-lapse geochemistry.
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.
Contact Info
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Product
Resources
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.
