Quantification of Proppant Distribution Effect on Well Productivity and Recovery Factor of Hydraulically Fractured Unconventional Reservoirs

Abstract

The most common completion methodology the industry uses to help maximize productivity and fluid recovery in unconventional reservoirs consists of placing multiple, optimally spaced transverse fractures in horizontal wells, navigating along the direction of minimum principle horizontal stress. In this type of completion, well productivity and fluid recovery can be maximized when the following conditions are met: Horizontal wellbore navigates optimally in the reservoir. Generated fracture connects the entire productive pay zone. Transverse fractures are optimally spaced. Proppant is well-distributed throughout the created fracture. With respect to the actual completion strategy, the first two conditions are met using proper geological interpretation and measurements of fracture height growth (e.g., microseismic); the third condition depends on economics and cluster efficiency. However, the distribution of proppant within the hydraulic fractures is usually ignored, particularly for cases in which low-viscosity fracturing fluids are used for stimulation. By performing extensive simulations for gas-producing reservoirs with a wide range of unconventional reservoir permeabilities, this paper quantifies the impact of proppant distribution on well productivity and the recovery factor (RF). For cases in which proppant distribution is not optimized, previously published extensive simulations demonstrate that the RF and productivity are significantly affected.

New Findings in Expected Ultimate Field Recoveries: Implications of Staggered Lateral Downspacing in the Eagle Ford Shale

“…An extensive review of over 100 fractured fields was performed by Allan and Qing Sun (2003) that found typical oil recoveries for Type II/III solution gas drive reservoirs between 1525% and total average Type II/III recoveries between 20-30%. Work by Aguilera (1999) establishes Type II/III gas recoveries at 75-85%, which is similar to modeling by Sierra et al (2014) that predicts, given optimal completion strategies, shale gas recoveries of up to 70% can be achieved (Figure 1). The power of this exercise is to validate that further recovery enhancement can be achieved by implementing multi-zone (staggered) lateral placement.…”

“…This suggests that the assumption of a dynamic recovery factor is fundamentally related to fracture geometry, stimulation effectiveness and reservoir (net pay) height. Published examples of recovery factors in unconventional shale gas and oil reservoirs is limited, with authors attempting to predict it through various modeling techniques (Wan et al, 2013, Sierra et al, 2014. As such, it was decided to use naturally fractured reservoirs with similar matrix permeabilities as analogs to gain insight into the potential range and limits of recoveries.…”

Coupled Geomechanics and Fluid Flow Model for Production Optimization in Naturally Fractured Shale Reservoirs

“…The recovery factor (RF), or the recoverable amount of hydrocarbon initially in place, is typically optimized in unconventional reservoirs by ideal placement of the horizontal wellbore in the reservoir, fracture connectivity to the entire productive pay zone, effectively spaced transverse fractures, and well-distributed proppant within the created fracture (Sierra et al, 2014). Prior to the optimization runs, the initial oil and gas recovery factors were both 12% for the Zipper well case as calculated by Equations 7.1 and 7.2:…”

Permeability of large‐scale fractures with ununiform proppant distributions in coalbed methane development

“…15,16 During long-term oil and gas production, the distribution of proppants in fractures directly controls the residual aperture and permeability of hydraulic fractures, which impacts the productivity and financial advantages of hydrocarbon development. [17][18][19] Countless computational and experimental investigations have been carried out continually to uncover the impact of proppant distribution on fracture permeability and conductivity. However, millimeter-scale fractures filled with proppants are used as research objects in a portion of numerical simulation.…”