Executive Summary

To keep up with the pace of the large number of manuscripts we receive for peer review in SPE Reservoir Evaluation and Engineering, I have recruited three new associate editors. I would like to welcome Selin Erzeybek, Zoya Heidari, and Siddharth Misra to the editorial board; they bring extensive knowledge in various subject matters, youth, and diversity to our journal. In other news, sunsetting of SPE Economics & Management was completed in October. In the future, readers will see some papers on this topic published in SPEREE, including data analytics, portfolio/asset management, project valuation, and petroleum economics.
  The last issue of 2017 brings us 19 papers covering various topics—namely, enhanced oil recovery, formation evaluation, fractured reservoir modeling, geostatistics, heavy oil, reservoir characterization, unconventional reservoirs, and well testing. SPE has moved to a single-column layout to better support the digital format of our journals. While we transition from two-column to single-column, readers will see a mix of the two formats over the next few months until we clean the paper backlog in Preprint. 

Enhanced Oil Recovery (EOR). The EOR section presents three papers covering laboratory and modeling work flows. The first paper by Luo et al. is a combination of simulation and upscaling of laboratory measurements for water and polymer floods to characterize viscous fingering. Next, Boeije et al. propose a surfactant-screening methodology for foam EOR in an oil-wet reservoir with bulk-foam tests and foam flooding in model porous media. In the third paper, Namani et al. describe an experimental setup to investigate the advantage of segregation of water-above-gas injection that is subsequently confirmed by means of upscaled reservoir conditions.

Formation Evaluation (Petrophysics). Ali et al. combine various logs to calculate fluid and rock properties in a carbonate heavy-oil reservoir. Note that I struggled with placing this first paper in this section because it deals with heavy oil; however, I consider that a paper dealing with advance logs such as multifrequency dielectric and nuclear magnetic resonance (NMR) would be more appealing to the petrophysics community. Next, Cheng and Heidari propose a new application of the NMR log-inject-log method to improve the assessment of permeability and to distinguish isolated from connected pores in the porous media. 

Fractured Reservoir Modeling. This section brings us two compelling papers. First, Ozkaya explains how the location, size, and shape of interconnected-conductive-fracture bundles can be determined by integrating borehole image data with depletion curve analysis in a reservoir in the Middle East. Then, Wehunt et al. present an example of stochastic 2D well-path assessment in a naturally fractured carbonate reservoir in Kazakhstan; the model was calibrated with production logs to reproduce production results in observation wells above the oil/water contact. 

Geostatistics. This section presents cases of statistical methods for data analysis and reservoir simulation. Saleh et al. present a comprehensive study of public data on polymer flooding that shows the use of simple statistical methods to classify the data sets in three categories—namely, field, pilot, and laboratory. Chiotoroiu et al. propose a method of production forecasting in a polymer-flooding pilot. The method combines geological sensitivity and clustering with dynamic calibration steps to improve the reliability of probabilistic forecasting of the incremental oil recovery. Xu and Forouzanfar et al. study the application of information content and integration of distributed-temperature-sensing data for near-wellbore reservoir characterization. They make use of various techniques to analyze the data and make predictions, such as the principle of information theory, the ensemble-smoother-with-multiple-data-assimilation algorithm, history matching, and doubly stochastic modeling, for estimating properties in a synthetic layered reservoir.

Heavy Oil. Three papers on heavy oil are presented in this section. Kumar et al. describe the evolution of primary and thermal recovery in an extraheavy-oil field in South America; the authors provide a novel probabilistic work flow for a full-field development plan to provide robust forecast during the entire life cycle. Nourozieh et al. present measurements of density and viscosity at pressure and temperature for various oil samples in the Canada oil sands and discuss models for viscosity prediction in oil/solvent mixtures and its application on steam-assisted-gravity-drainage projects. Then, the section closes with a paper by Xiao and Zhao proposing the concept of effective wormhole coverage as a proxy of the drainage region of cold-heavy-oil-production-with-sand wells with complex wormhole networks. The authors conclude that these types of wells have distinctive pressure and production behavior that can be better analyzed by type-curve matching instead of numerical simulation.

Reservoir Characterization. This section features two papers using seismic attributes to estimate petrophysical properties for reservoir modeling. Namadarian et al. use seismic-derived acoustic impedance volumes to predict porosity in a gas-injection study. The predicted 3D geocellular grid is then used as an input to predict gas fingering in the dynamic model to reconsider field-development strategy. Adeosho et al. show an integrated petrophysical characterization with seismic attributes maps to reveal geobodies below seismic resolution. This study was used to evaluate the drilling of new infill wells to improve oil production in Niger Delta field. 

Unconventional Reservoirs. The hot topic of unconventional reservoirs brings us three compelling papers. Yu et al. combine fracture propagation modeling and reservoir simulation to optimize production in a shale gas reservoir. The authors developed a semi-analytical model to simulate gas production from nonplanar fracture geometry by fully coupling elastic deformation of the rock and fluid flow. Tinni et al. present a pore connectivity study between different wettability systems in organic-rich shales. By sequential spontaneous imbibition of brine and dodecane, they show the presence of water-wet, hydrocarbon-wet, and mixed-wettability pores. They conclude that up to 3 wt% total organic carbon is a necessary (but not sufficient) condition for developing connectivity throughout organic bodies. Finally, Norbisrath et al. introduce a study to assess relationships between low-frequency complex resistivity spectra, nanopore geometry, and mineralogy to estimate rock parameters critical for the evaluation of resistivity-based hydrocarbon saturation, storage, and producibility. The study was carried out with advanced imaging techniques in samples from the Vaca Muerta mudrocks in Argentina.

Well Testing. In the last paper of this issue, McClure discusses the deflection observed in log-log superposition-time derivative plots to identify flow regimes in well tests with variable rate. He argues that if such plots are used to interpret diagnostic fracture-injection (DFIT) tests, the deflection observed in the superposition-time derivative does not represent actual reservoir or transient behavior. Field examples and recommendations are provided for proper DFIT interpretation.

The editorial board has made every effort to bring you a robust issue by selecting innovative and useful manuscripts from industry and academia. All papers were carefully reviewed by at least two technical editors under the coordination of an associate editor. However, conclusions and interpretation stemmed from these papers are opinions and observation of the authors. Because knowledge sharing and open discussions are important, SPE welcomes further discussion from our readers. I look forward to receiving discussion letters.

Happy reading!

Jesús M. Salazar, SPE Res Eval & Eng Executive Editor,