Free fall and controlled gravity drainage processes in fractured porous media: Laboratory and modelling investigation

Abstract

Gravity drainage is known to be one of the most effective methods for oil recovery in fractured reservoirs. In this study, both free fall and controlled gravity drainage processes were studied using a transparent fractured experimental model, followed by modelling using commercial CFD software. The governing equations were employed based on the Darcy and mass conservation laws and partial pressure formulation. Comprehensive examination was done on variables such as fluid saturation, velocity, and pressure distribution in the matrix and fracture, as well as fluid front level and production rate. Additionally, effects of the model parameters on the gravity drainage performance were investigated. The experimental results confirmed a higher oil recovery factor at breakthrough for lower production rates in the controlled gravity drainage. Satisfactory agreement was observed between the experimental data and modelling results.

Experimental and Modelling Study of Gravity Drainage in a Three-Block System

“…Major results reported by researchers in this field could be classified into two general categories: first, increasing the model height and decreasing capillary pressure improve the process efficiency; second, the presence of a driving viscous force leads to earlier breakthrough and can improve the ultimate recovery factor (i.e., forced gravity drainage). Notably, lower recovery factor by increasing the gas injection rate is also reported after a critical gas injection rate (Rostami et al 2010;Akhlaghi et al 2012;Saedi et al 2015;Zobeidi et al 2016). Firoozabadi and Markeset (1992) and Firoozabadi and Markeset (1994) used spacers of different thicknesses (up to 1.2 mm) as horizontal fractures in a multi-stack block system.…”

“…Numerous experimental studies have been conducted on the gravity drainage mechanisms. The majority of these studies were performed on synthetic porous media such as coarse quartz grains sand packs with high permeability, so that the duration of each experiment, as well as the set-up height, can be adequately decreased (Moon and Bruce 2007;Zendehboudi et al 2011;Saedi et al 2015;Teng et al 2016). Saidi et al (1979) studied the interaction of matrix blocks and the presence of capillary continuity and reinfiltration between adjacent matrix blocks.…”

“…Gravity drainage modelling can be categorized as analytical (Bech et al 1991;Di Donato et al 2006;Abbasi et al 2018), numerical (Schechter and Guo 1996;Chow and Butler 1996;Saedi et al 2015;Udoh et al 2015;Dejam 2018;Rahmati and Rasaei 2019) and empirical-experimental (Li and Horne 2003;Zendehboudi et al 2011) models. Some researchers investigated the gravity drainage mechanisms in tight rocks by introducing film flow phenomena (Nenniger and Storrow 1958).…”

How do you write and present research well? 8 — Assign authorship according to intellectual involvement

“…r Preparing or editing figures [46] r Supplying samples [47] r Supplying data r Writing programs [38] r Discussing the results [48] r Editing and proofreading [40,36] r Access to departmental facilities [49] …”

Review of studies on pore-network modeling of wettability effects on waterflood oil recovery

“…Some studies have investigated the effects of wettability in fractured and homogeneous porous media during free-fall gravity drainage (FFGD) and controlled gravity drainage (CGD) conditions (Zendehboudi et al, 2011;Zendehboudi et al, 2012;Maroufi et al, 2013;Saedi et al, 2015). These studies have shown that different wettability conditions govern the oil recovery mechanism during FFGD and CGD processes.…”