Executive Summary

I would like to take this opportunity to thank SPE for the honor to serve as the co-executive editor of SPE Reservoir Evaluation & Engineering (under the discipline of reservoir engineering) and to thank Gary Teletzke for his outstanding contributions while serving in this role. Gary will continue to support SPEREE as editor for a special issue of select papers on Unconventional Resources slated for November 2018. Several of these papers will also be spotlighted in the upcoming May 2018 issue. 

I would also like to recognize and thank outgoing and incoming SPEREE associate editors Gavin Longmuir and Bailian Chen, and all SPEREE associate and technical editors for accepting the responsibility and volunteering countless hours to ensure quality reviews and technically sound recommendations. I look forward to working with all of you and the editorial staff at SPE in continuing the legacy of timely publications of novel technologies and case studies in SPEREE

A total of 15 papers were selected and included in this issue, covering well testing, reservoir characterization, enhanced oil recovery, petrophysics, and brownfield rejuvenation. Below is a summary of each paper in this issue. 

Well Testing

A New Method for Production-Data Analysis and Well Testing by Use of Superposition Rate  presents the development of superposition-rate functions using the superposition principle to analyze production and well-test data for transient (radial, linear, and bilinear) and boundary dominated flow. A key improvement of this approach, as compared to the classical superposition time method, is that the data can be analyzed in real time.  

Rate Dependence of Bilinear Flow in Unconventional Gas Reservoirs  introduces a new correction factor that accounts for the rate dependency of bilinear flow during early production in fractured gas wells. This correction reduces the error that occurs when applying existing rate-transient analysis (RTA) methods to bilinear flow as a result of nonlinearities in the gas-diffusivity equation.  

Temperature Transients Affect Reservoir-Pressure Estimation During Well Tests: Case Study and Model  presents a study on the effect of temperature changes on measured pressures during drill-stem testing that demonstrates that the placement of downhole gauges and nonisothermal effects in the wellbore can dramatically impact measured pressures in highly productive wells. 

Reservoir Characterization

Multiple-Point Geostatistical Lithofacies Simulation of Fluvial Sand-Rich Depositional Environment: A Case Study from Zubair Formation/South Rumaila Oil Field  presents a case study on using multiple-point facies (MPS) geostatistics to model the 3D lithofacies distribution of the fluvial sand-rich depositional environment in Iraq’s South Rumaila field. Results demonstrate MPS is an efficient approach to reconstruct complex geological reservoirs and effectively preserves reservoir heterogeneity and connectivity of flow paths. 

Decoupling of Channeling and Dispersion Effects by Use of Multiwell Tracer Test  introduces a new formulation to study tracer propagation along streamlines in heterogeneous reservoirs that enables decoupling of small-scale heterogeneity (dispersion) and channeling effects using multiwell tracer data. 

Investigating Gas-Adsorption, Stress-Dependence, and Non-Darcy-Flow Effects on Gas Storage and Transfer in Nanopores by Use of Simplified Local Density Model provides insight into the effects of gas adsorption, stress dependencies, and non-Darcy flow on gas storage and transfer in nanopores of shale-gas reservoirs, and introduces a methodology to calculate effective porosity and permeability as a function of these parameters on the basis of the simplified local density (SLD) model. 

Mechanistic Modeling of Clay Swelling in Hydraulic-Fractures Network  presents a mechanistic approach to model clay swelling in various rock mineralogies, including the Barnett, Eagle Ford, and Marcellus shales, and investigates the associated production loss in the hydraulic-fracture networks of these shales. Results indicate the degree of conductivity damage and production loss induced by clay swelling varies in different shale formations and was more significant in the clay-rich Barnett shale relative to the calcite-rich Eagle Ford and Marcellus shales. 

Enhanced Oil Recovery

A Case Study on Simulation of In-Situ CO2 Huff-‘n’-Puff Process presents laboratory and modeling results of a case study for an in-situ COhuff-‘n’-puff (ISCHP) EOR process that was undertaken after obtaining encouraging results from a pilot in the Jiangsu field in China. Results provide an improved understanding of in-situ gas generation, recovery mechanisms, and primary operating parameters such as injection volumes, reagent concentrations, and soak time for evaluating the feasibility of ISCHP for EOR

Laboratory Tests and Modeling of Carbon Dioxide Injection in Chalk With Fracture/Matrix-Transport Mechanisms  investigates the fundamental transport mechanisms of CO2 injection in fractured chalk core at reservoir conditions through extensive experimental and modeling work. Results provide insight on transport mechanisms, including dispersion that was found to be particularly important, as well as comprehensive laboratory, pressure/volume/temperature, and modeling data that may benefit further research and field application.

Enhanced Oil Recovery in Liquid-Rich Shale Reservoirs: Laboratory to Field investigates EOR gas injection, including CO2, a C1/C2 mixture, and N2 in liquid-rich shale reservoirs. Results from laboratory experiments performed on Bakken core and reservoir modeling indicate the primary oil-recovery mechanism is miscible oil extraction in the matrix/fracture interface region. However, controlling factors include repressurization, oil swelling, viscosity, and interfacial-tension (IFT) reduction, diffusion/advection mass transfer, and wettability alteration. 

Estimation of Foam-Flow Parameters for Local Equilibrium Methods by Use of Steady-State Flow Experiments and Optimization Algorithms presents a methodology to estimate foam-model parameters from laboratory data and investigates foam behavior for a given range of water saturation for two local equilibrium models. Results show the parameter-estimation method coupled with an optimization algorithm successfully matches experimental data with both models. 

Interface Renewal and Concentration Shock Through Sloughing: Accounting for the Dissonance Between Production Models and Measured Outcomes for Solvent-Assisted Bitumen-Production Processes presents an analysis of the discrepancy in production rate between experimental measurements and semi-analytical models for solvent-assisted bitumen processes. Results illustrate a new discrete flow-and-diffusion mechanism, coined sloughing, can account for the higher production rates observed experimentally. 

Petrophysics

Petrophysical Quantification of Multiple Porosities in Shale-Petroleum Reservoirs With the Use of Modified Pickett Plots introduces a methodology to estimate adsorbed, organic, inorganic, and fracture porosities using modified Pickett plots for quantifying the storage capability of shale reservoirs. 

Effect of Water Salinity and Water-Filled Pore Volume on High-Frequency Dielectric Measurements in Porous Media presents a quantitative study on the effects of water salinity and saturation on dielectric-permittivity measurements of brine at high frequencies ranging from 1 MHz to 3 GHz. Results from this study can potentially improve the interpretation of dielectric-permittivity measurements for a more reliable assessment of water-filled porosity and hydrocarbon saturation. 

Brownfield Rejuvenation

A Reversed Geo-Dynamic Approach for Brownfield Rejuvenation  introduces a geo-dynamic field modeling (GDFM) work flow for evaluating brownfields. This approach consists of rearranging existing elements of the reservoir evaluation process to obtain a purpose-driven, deterministic reservoir model that can quickly result in development scenarios. 

Jasper Ring, SPE Res Eval & Eng Executive Editor, 
Chevron Europe, Eurasia and Middle East E&P