van Batenburg

This is the December and final issue of SPE Reservoir Evaluation & Engineering for 2012. It brings you 10 papers that reflect areas of current activity in the industry. Four papers focus on permeability evaluation of (tight) reservoir rocks. Two papers on thermal processes cover simulation studies for heavy-oil recovery. There are three papers that provide laboratory and field data for different improved and enhanced-oil-recovery processes. The final paper covers a method for production performance diagnostics.

Permeability Evaluation

Quantifying the Role of Grain Lining Hematite Cement in Controlling Permeability in a Relatively Tight Gas Sandstone Reservoir From the North Sea contains a study that illustrates the presence of hematite as a major controlling factor on the permeability of the relatively tight-sandstone reservoir in the North Sea. The results suggest that the presence of illite is not the dominant factor that determines the permeability. Integrated Permeability Analysis in Tight and Brecciated Carbonate Reservoir presents a case study on different methods of permeability evaluation in a complex carbonate reservoir. A combination of methods can be helpful, but permeability assessment remains a considerable challenge for heterogeneous reservoirs. Evaporite-Distribution Typing from Resistivity Images and Openhole Logs in a Middle Eastern Reservoir describes a study that used resistivity images, conventional openhole logs, and core data of a Middle-Eastern dolomite reservoir to help distinguish which nodular forms of anhydrite are related to permeability reduction. Nanopore-Structure Analysis and Permeability Predictions for a Tight Gas Siltstone Reservoir by Use of Low-Pressure Adsorption and Mercury-Intrusion Techniques presents pore-size distribution data for a western Canadian tight gas/shale reservoir determined by means of low-pressure nitrogen adsorption and mercury injection capillary pressure measurement. There is reasonable agreement between the interpreted pore-size distributions from the nitrogen-adsorption data and mercury-injection data for the portion of the pore-size distribution sampled by both. Subsequently, the dominant pore-throat size was used to predict absolute permeability and compare the resulting permeability to laboratory-derived values for some samples.

Thermal Processes

Numerical Simulation of Steam-Assisted Gravity Drainage With Vertical Slimholes presents results of a simulation study that explores how the negative effects of low-permeability shale barriers on steam-assisted gravity-drainage (SAGD) performance and bitumen recovery can be overcome by drilling vertical holes through those barriers. Reservoir Simulation of Steam Fracturing in Early-Cycle Cyclic Steam Stimulation demonstrates that appropriate simulation of cyclic steam stimulation (CSS) should include geomechanics: modeling flow and heat transfer alone is not sufficient to predict bottomhole pressures from steam- injection rates.

Improved and Enhanced Oil Recovery

Lessons Learned From Applications of a New Organic-Oil-Recovery Method That Activates Resident Microbes reports results of a series microbial-enhanced Oil recovery (MEOR)-like treatments, in which the microbes existing in the reservoir are stimulated by injection of appropriate nutrients. Wettability Survey in Bakken Shale With Surfactant-Formulation Imbibition shows that there are surfactants that could potentially help to improve oil recovery from tight-oil reservoirs such as the Bakken Shale. Qualitative and Quantitative Analyses of the Three-Phase Distribution of Oil, Water, and Gas in Bentheimer Sandstone by Use of Micro-CT Imaging presents micro-CT data interpretation that confirms that spreading oil films in strongly water-wet rock three-phase oil, water, and gas systems are present in strongly water-wet Bentheimer sandstone.

Production Diagnostics

Production-Performance Diagnostics Using Field-Production Data and Analytical Models: Method and Case Study for the Hydraulically Fractured South Belridge Diatomite describes an elegant production performance diagnostic method that is illustrated with numerous examples from the South Belridge field in California.

These papers were all reviewed and ultimately approved in the peer-review process. However, the conclusions presented in these papers are not cast in stone. Because sharing of knowledge and experiences is essential, SPE welcomes further "discussion" of any paper published in any SPE journal. Therefore, please feel free to submit a discussion of a paper to SPE if you disagree with interpretations or conclusions presented or if the authors and reviewers have missed publications that either support or invalidate results. I look forward to receiving such discussion letters.

Diederik van Batenburg, Shell
Co-Executive Editor of SPE Res Eval & Eng