Application of Inter-Fracture Injection and Production in a Cluster Well to Enhance Oil Recovery

Abstract

Applications of cluster wells and hydraulic fracturing enable commercial productivity from unconventional reservoirs. However, well productivity decrease rapidly for this type of reservoirs, and in many cases, it is difficult to maintain a productivity that is economical. Enhanced oil recovery (EOR) is therefore needed to improve well performance. Traditional fluid injection from other wells are not feasible due to the ultra-low permeability, and fluid Huff-n-Puff also fails to meet the expected recovery. This work investigates the feasibility of the inter-fracture injection and production (IFIP) approach to increase oil production of multiple multi-fractured horizontal wells (MFHW). Three MFHWs are considered in a cluster well. Each MFHW includes injection fractures (IFs) and recovery fractures (RFs). The fractures with even and odd indexes are assigned to be IFs or RFs, respectively. The injection/production schedule falls into two categories: synchronous inter-fracture injection and production (s-IFIP) and asynchronous inter-fracture injection and production (a-IFIP). To analyze the well performance of multiple MFHWs using the IFIP method, this work performs numerical simulation based on the compartmental embedded discrete fracture model (cEDFM) and compares the production performance of three MFHWs using four different producing methods (i.e., primary depletion, CO2 Huff-n-Puff, s-IFIP, and a-IFIP). Although the number of producing fractures is reduced by about 50% for s-IFIP and a-IFIP, they achieve much higher oil rates than primary depletion and CO2 Huff-n-Puff. Sensitivity analysis is performed to investigate the impact of parameters on the IFIP. The fracture spacing between IFs and RFs, CO2 injection rates, and connectivity of fracture networks affect the oil production significantly, followed by length of RFs, well spacing among MFHWs and length of IFs. The suggested well completion scheme is presented for the a-IFIP and s-IFIP methods. This work demonstrates the ability of the IFIP method in enhancing oil production of multiple MFHWs in unconventional reservoirs.

Evaluation of the Effectiveness of Continuous Gas Displacement for EOR in Hydraulically Fractured Shale Reservoirs

“…The overall recovery observed for hydrocarbon gas (8.74%) was very similar to that for CO 2 (8.26%), and the difference was attributed to differences in the compressibility, viscosity, and phase behavior of the injected fluids. This observation was supported by Hoffman (2012), who reported that the injections of hydrocarbon gas and CO 2 were similarly effective as EOR methods. Du and Nojabaei (2019) reviewed the state of the gas-injection-based EOR in shale reservoirs, covering the spectrum of available information on the subject at the time.…”

“…Using very coarse 2D areal grids, Zhu et al (2017) investigated by means of numerical simulation the performance of the interfracture injection and production system proposed by Dombrowski et al (2015) and reported significant incremental recoveries of oil after 5,000 days of CO 2 injection into shale reservoirs of various permeabilities and conducted an extensive sensitivity analysis. The authors proposed hydrocarbon gas as an alternative to CO 2 because of its lower cost, easy availability, lower viscosity (expected to lead to a higher injectivity and a faster oil recovery), and similar oil recovery performance-in agreement with the observations of Hoffman (2012) and Gala and Sharma (2018). He et al (2019) used a compartmental embedded discrete fracture model to study numerically the application of the interfracture injection and production approach in a cluster well using CO 2 as the injection gas.…”

“…Shale gas and shale oil are now among the main contributors to US hydrocarbon production (King 2010;US EIA 2020a, 2020b, 2020c. This remarkable success has been matched by similar progress in the production of (relatively) low-viscosity liquid hydrocarbons, including condensates, but significant challenges to liquid flow posed by the ultralow permeability (ULP), high capillary pressures, and high irreducible liquid saturations of such reservoirs have limited liquids production to a very low fraction (<10%) of the resources-in-place (Hoffman 2012;Zuloaga-Molero et al 2016;Patzek et al 2017;Cronin et al 2019). Increasing the recovery of liquids from these ULP systems even by 50 to 100% over the current, very low levels not only will increase production and earnings but will also have considerable wider economic implications because the enhanced recovery will affect reserves and the valuation of companies.…”

“…The study of Hoffman (2012) was among the first numerical investigations of the performance of gas flooding (involving CO 2 and miscible and immiscible hydrocarbons) as EOR methods for increased production and recovery from shale oil reservoirs at the Elm Coulee Field. Following a 3.25-year-long period of primary production, gas was injected continuously for 20 years.…”

Effects of Wettability and Minerals on Residual Oil Distributions Based on Digital Rock and Machine Learning

“…Enhancing oil recovery (EOR) is crucial for oilfields to obtain stable oil production. Water flooding is a dominating enhanced oil recovery technique owing to its low cost, easy operation, and less pollution [1][2][3][4]. Therefore, it is significant for EOR to study the transport mechanisms of multiphase flow and distribution characteristics of fluids.…”