Understanding Shale Performance: Performance Analysis Workflow with Analytical Models in Eagle Ford Shale Play

Abstract

Tight oil and shale gas resources produced 29% of total US crude oil and 40% of total US natural gas in 2012 (EIA). Technically recoverable quantities of shale gas and shale oil resources for the US are 665 trillion cubic feet and 58 billion barrels, respectively. Considering the impact of the "unconventional boom" on the economy, it is crucial to understand the production performance of wells to maximize the recovery from shale plays. The latest advances in Rate Transient Analysis (RTA) provide quick yet robust tools to assess the quality of the Stimulated Rock Volume (SRV) and long term performance of the wells by estimating EURs. The most common challenge in history-matching of production in shale gas/oil wells has been the non-uniqueness of the history-matched parameters. A lot of emphasis has been put on estimation of fracture half-length, which is believed to be a primary driver for the performance of shale gas/oil wells. Since linear flow is the main transient flow regime in the early life of a hydraulically-fractured shale gas/oil well, a Rate Normalized Pressure (RNP) versus Square Root of Time plot is the most commonly used diagnostic plot for the performance analysis of the wells. A*sqrt(k) or xf*sqrt(k) parameter groups are reported as a proxy for productivity in hydraulically fractured shale/gas oil wells. Besides having permeability as an unknown, the history-match is also sensitive to net hydraulic fracture height, which is one of the inputs to models that must be specified from other sources of information. This paper presents a novel approach for production performance analysis of shale gas/oil wells, which significantly reduces the non-uniqueness issues that one can have in comparison of performance. Twenty two Eagle Ford Shale wells were analyzed across the trend from lean gas to high-yield condensate to define a workflow that could be applied to other wells in different geologic areas, yet provide consistent comparison of long term performance (EURs).

An Analytical Model for Analyzing and Forecasting Production From Multifractured Horizontal Wells With Complex Branched-Fracture Geometry

“…The production data of this example, which are presented in Figs. 22 and 23, were extracted from the paper by Stalgorova and Mattar (2012). We see that the BHP declines during early days of production, and then remains relatively constant during the late period.…”

“…These models represent an excellent attempt to capture a greater range of reservoir and fracture properties associated with MFHWs completed in low-permeability formations. The TLF and EFR models have been successfully applied to model complex well behavior exhibited in the field (Stalgorova and Mattar 2012;Samandarli et al 2014). Very importantly, these models have also been used in parallel with local (straight-line) solutions for reservoir and hydraulic-fracture characterization.…”

Pressure Transient Analysis of Multi-Fractured Horizontal Well in Tight Gas Reservoirs

“…Later, Stalgorova and Mattar extended the tri-linear flow model to a five regions flow model [12] . Then some researchers (Samandarli et al, 2014;Clarkson et al, 2013Clarkson et al, , 2014 successfully used these models to study the complex well behavior exhibited in the field [13][14][15] . Recently, Sureshjani and Clarkson developed a new enhanced fracture-region model based on the five regions flow model, and the new model is more general and rigorous than previous models [16] .…”