Executive Summary

First, I would like to recognize outgoing associate editors Alana Leahy-Dios and Byron Haynes for their contributions while serving on the SPE Reservoir Evaluation & Engineering (SPEREE) editorial review committee and welcome incoming associate editors Mark Schrader and Rod Batycky. I would also like to thank the SPEREE editors and the SPE staff for the timely production of select papers on unconventional resources that were spotlighted in the May 2018 issue and that will appear exclusively in the upcoming November 2018 special edition of SPEREE. Currently, there is a significant global interest in the assessment and development of unconventional oil and gas resources resulting in a substantial increase in research and application of new technologies in this area, especially within the reservoir evaluation and engineering community.

In this current issue of SPEREE, a total of eighteen papers are included on a variety of topics that cover unconventional resource evaluation, reservoir management, formation evaluation, reservoir characterization, reservoir modeling, smartwater flooding, and heavy oil. Below is a brief description of these papers. Also included in this issue is a discussion on SPE-181751-PA, Prediction of Resistivity Index by Use of Neural Networks With Different Combinations of Wireline Logs and Minimal Core Data, which originally appeared in SPEREE February 2017.

Unconventional Resource Evaluation

Mexican Unconventional Plays: Geoscience, Endowment and Economic Considerations  examines oil and gas resources and development economics in Mexico’s shale basins, including the Burgos, Sabinas, Tampico, Tuxpan (Platform), Veracruz, and Chihuahua basins.

Reservoir Management

Production-Pressure-Drawdown Management for Fractured Horizontal Wells in Shale-Gas Formations evaluates the effect of depletion-induced in-situ stress variations on productivity in unconventional shale-gas reservoirs, and shows that substantially higher ultimate recoveries can be achieved with proper management of pressure drawdown at lower initial production rates. 

Material Balance Applied to Dynamic Reservoir-Surveillance Patterns introduces a novel pattern material-balance approach for estimating remaining fluids in place and pressures over time as an alternative to flow simulation by applying material balance on streamline-derived pattern volumes.

Prognosis for Safe Water-Disposal-Well Operations and Practices That Are Based on Reservoir Flow Modeling and Real-Time Performance Analysis provides a simple diagnostic method and procedure for safe water-disposal operations, which will help disposal-well management become more economical and environmentally friendly.

Formation Evaluation

First Application of Logging-While-Drilling Deep-Azimuthal Resistivity Tool and Advanced Data-Interpretation Software for Reservoir Navigation at West Salym Field in Russia illustrates the capabilities of modern reservoir-navigation technology using deep-azimuthal resistivity technology and advanced data-interpretation software for two horizontal wells in the West Salym Field, Russia.

Effect of Internal Magnetic-Field Gradients on Nuclear-Magnetic-Resonance Measurements and Nuclear-Magnetic-Resonance-based Pore-Network Characterization quantifies the effect of internal magnetic-field gradients and spatial distribution of matrix components, such as clay minerals, on nuclear-magnetic-resonance (NMR) response, and shows the influence of these parameters on the NMR-based evaluation of porous media.

Phase Behavior in Shale Organic/Inorganic Nanopores From Molecular Simulation investigates the effect of pore material on fluid-phase behavior in shale reservoirs and provides a better understanding of phase diagrams in different shale environments.

Reservoir Characterization

Calculation of Estimated Ultimate Recovery and Recovery Factors of Shale-Gas Wells Using a Probabilistic Model of Original Gas in Place presents the development of a more-accurate original-gas-in-place (OGIP) model that is used to probabilistically asses OGIP, ultimate recovery, and recovery factor for shale-gas reservoirs.

Rock Typing in Eagle Ford, Barnett, and Woodford Formations presents an integrated work flow for rock typing with laboratory petrophysical measurements that results in the identification of three rock types found in the Eagle Ford, Barnett, and Woodford Formations.

Natural Fractures and Mechanical Properties in a Horn River Shale Core From Well Logs and Hardness Measurements presents a study on the formation of natural fractures in the Horn River Group, a major Canadian shale-gas play, and addresses relationships between natural-fracture development and rock-mechanical properties derived from cores and well logs.

Reservoir Modeling

Combining Physics, Statistics, and Heuristics in the Decline-Curve Analysis of Large Data Sets in Unconventional Reservoirs introduces a physics-based decline-curve model for horizontal multistage-hydraulically-fractured wells that is applied to a large data set in a work flow that incorporates heuristic knowledge into history matching and uncertainty quantification. 

Extension of Dykstra-Parsons Model of Stratified-Reservoir Waterflood To Include Advanced Well Completions extends the Dykstra-Parsons method to include wells with various well-completion and control options for rapid prediction of waterflood performance, and provides a simple means of estimating the long-term value derived by controlling zonal flow rate.

A Semianalytical Method for Modeling Two-Phase Flow in Coalbed-Methane Reservoirs With Complex Fracture Networks introduces an efficient semianalytical model to predict gas and water production in coalbed methane reservoirs with multiscale fracture networks, and illustrates the effects of fracture-network complexity/connectivity and stress sensitivity on gas/water-production behavior.

Smartwater Flooding

Effect of Salinity and Water Ions on Electrokinetic Interactions in Carbonate Reservoir Cores at Elevated Temperatures introduces a new procedure to measure the time-dependent effects of the displacement of seawater by smartwater on surface charge in carbonate reservoir cores and confirms the beneficial effect of smartwater on wettability alteration.

Heavy Oil

Similarity of the Effect of Different Dissolved Gases on Heavy-Oil Viscosity presents an analysis of viscosity for mixtures of different gases dissolved in heavy oils, which illustrates that the reduction in oil-phase viscosity is almost the same for all the gas mixtures.

The Potential for Surface Mining a Heavy-Oil Reservoir: The Example of the Ratqa Lower Fars in the State of Kuwait investigates the feasibility of surface mining the viscous crude oil of the Ratqa Lower Fars reservoir in northern Kuwait and illustrates that oil rates may be sustainable and profitable.

Investigation of Post-Abandonment Surface Subsidence in Steam-Assisted-Gravity-Drainage Operations investigates the mechanisms driving surface heave and subsidence associated with a steam-assisted-gravity-drainage (SAGD) pilot, and quantifies the magnitude of surface subsidence and induced shear stresses in nearby developmental wells.

Senlac, the Forgotten SAGD Project presents a complete case study of a heavy-oil SAGD project in Saskatchewan, Canada, where oil is mobile, and illustrates the potential use of this technology in thinner and smaller reservoirs.

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