Executive Summary

This issue of SPE Res Eval & Eng brings you fourteen papers that reflect areas of current activity and interest in the industry. Two papers focus on formation evaluation while drilling.  Another two papers are related to formation evaluation models and theory; two more papers are related to reservoir management and performance prediction. The industry’s continued interest in unconventional reservoirs is reflected in four papers on tight rock evaluation and performance prediction.  This interest is also reflected on one of the two papers on history matching. The final two papers deal with enhanced oil recovery.

Formation Evaluation While Drilling

New Software for Processing of LWD Extra-Deep and Azimuthal Resistivity Data provides a description of the algorithm and software implementation for real-time processing of any combination of the omni-directional, azimuthal, and extradeep LWD resistivity measurements.  The results can be used to make decisions to change the drilling direction in real-time.

Sampling While Drilling: an Emerging Technology presents the progress in sampling while drilling technology and paints a picture of what might be achievable in practice with this technology.

Formation-Evaluation Models and Theory

Formation Resistivity Theory: How Archie Equations, Shaly Reservoir Models, Conductive Rock Matrix Model and Dual/Triple Porosity Models are related presents the theory of formation resistivity in porous media based on the parallel resistivity model and then extends it for resistivity in series.  Archie’s saturation equation is theoretically explained by the presented theory.  New shaly-sand models for estimating HCPV are derived and field data are used to validate this work.

A Novel Infinite-Acting Radial-Flow Analysis Procedure for Estimating Permeability Anisotropy from an Observation-Probe Pressure Response at a Vertical, Horizontal, or Inclined Wellbore presents a new analyses procedure for estimating horizontal and vertical permeability from pressure-transient data acquired at a probe during an interval pressure test conducted with a single or dual probe or a packer module.

Reservoir Management and Performance Prediction

Experiences with an Efficient Rate Management Approach for the 8th Tortonian Reservoir in the Vienna Basin   presents a case history to illustrate that active well-rate management to promote the efficient use of injected fluids and to reduce fluid cycling is a simple way to increase recovery in brown fields while minimizing costs and preserving existing field/well-fluid-handling constraints.

New Method to Predict Performance of Gas Condensate Wells presents an analytic method to generate inflow performance relationship (IPR) curves for gas condensate wells that incorporates the effect of condensate banking as the pressure near the wellbore drops below the dew point.

Tight Rock Evaluation and Performance Prediction

Flow Units: from Conventional to Tight Gas to Shale Gas to Tight Oil to Shale Oil Reservoirs extends the concept of process or delivery speed (the ratio of permeability to porosity) that was previously defined for conventional, tight, and shale gas reservoirs to petroleum systems in general. It illustrates that distinctive flow units in each type of reservoir can empirically be linked to gas and oil rates and under favorable conditions to production decline.

The Use of Rate Transient Analysis Modeling to Quantify Uncertainties in Commingled Tight Gas Production Forecasting and Decline Analysis Parameters in the Alberta Deep Basin presents a RTA/DCA workflow that provides a fit-for-purpose way to quantify uncertainties in tight gas production forecasting by use of physical models, especially in cases when production history is limited and detailed field-level numerical simulation is not practical.

Analyzing Production Data from Hydraulically Fractured Wells: the Concept of Induced Permeability Field introduces an alternative model for production decline analysis of hydraulically fractured wells based on the concept of induced permeability field.  The model considers the case in which the fracturing treatment in addition to establishing the linear flow geometry in the drainage volume also alters the ability of the formation to conduct fluids throughout, but with varying degree depending on the distance from the main fracture plane.

Characterizing Hydraulic Fracturing with a Tendency for Shear Stimulation Test presents a procedure to determine relatively unambiguously the degree to which shear stimulation contributes to stimulation in a formation.  The procedure involves injection at a constant bottomhole pressure below the minimum principle stress.

History Matching

History Matching of The Norne Full Field Model Using an Iterative Ensemble Smoother describes the application of the iterative ensemble smoother to the history matching of the Norne field, a North Sea field, with a significant number of wells, a variety of data types, and a relatively long production history. Particular attention is focused on the problems of the identification of important variables, the generation of an initial ensemble, the plausibility of results, and efficiency.

3D Modeling of Multistage Hydraulic Fractures and Two-Way Coupling Geomechanics - Fluid Flow Simulation of a Horizontal Well in the Nikanassin Tight Gas Formation, Western Canada Sedimentary Basin nicely illustrates the need of having a two way coupling between geo-mechanics and fluid flow simulations for tight reservoirs and provides a workflow that can be followed to tackle similar situations.

Enhanced Oil Recovery

Four-fluid-phase, fully implicit simulation of surfactant flooding provides a description of the implementation of a reservoir simulator that contains a micro-emulsion phase behavior model based on oleic/aqueous/surfactant pseudo-phase equilibrium, as commonly used in chemical flooding simulators coupled to Gas/Oil/Water phase equilibrium resulting in four-fluid-phase research reservoir simulator.

Use of CO2 and Hydrocarbon Solvents during Steam-Over-Solvent Injection in Fractured Reservoirs (SOS-FR) Method for Heavy-Oil Recovery from Sandstones and Carbonates presents experimental data to evaluate if carbon dioxide and hydrocarbon solvent can be used in combination with steam to enhance the recovery of heavy oils from fractured reservoirs.

The above papers were all reviewed and ultimately approved in the peer-review process. However, the conclusions presented in these papers are not cast in stone. As sharing of knowledge and experiences is essential, SPE welcomes further “discussion” of any paper published in any SPE journal. Therefore, I urge you to submit a discussion of a paper to SPE if you have alternative views on methods, interpretations, and/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
Co-Executive Editor of SPE Res Eval & Eng