Executive Summary

Welcome to the June 2014 edition of SPE Journal. This issue brings you 17 outstanding papers, covering a wide spectrum of subjects that reflect areas of current activity and interest in the industry and academia. The following is a brief overview of each paper.

The issue begins with two papers that address the prediction of permeability and pressure distribution in unconventional gas reservoirs. The first paper introduces a new analytical coal-permeability-prediction method that accounts for reversal effects of temperature and effective stress on coalbed methane permeability. The second paper develops a semi-analytical method of characteristic solution for predicting the pressure distribution in a 1D matrix of shale gas by use of analogous-continuum approximation. The solution is fast and accurate, and includes the effects of compressibility, gas slippage, and desorption.

The next two papers address new experimental results on the retention of polymers in porous media and an analytical model for polymer-injectivity for enhanced-oil-recovery applications. The first paper in this category investigates the effect of hydrolyzed polyacrylamide (HPAM) polymer concentration on retention in porous media by conducting both static and dynamic experiments. The second paper presents an analytical polymer-injectivity model that is based on the Peaceman well model, and covers both shear-thinning and shear-thickening polymers. The model improves polymer-injectivity calculations, especially for coarse wellblock sizes.

The issue continues with three papers related to well-test and production analyses. The first paper in this category presents a graphical procedure for estimating the permeability-thickness product of a natural fracture and its skin from two representative values of measured pressure response. The second paper introduces a Laplace-transform-based finite-difference quasistationary solution method for efficiently and accurately simulating the pressure-transient behavior of water-injection and falloff tests. The last paper in this category investigates the interdependability and interchangeability of gas-well-performance forecasting by use of the rescaled exponential models for the boundary-dominated flow period under constant bottomhole pressure and on the basis of the use of pseudo variables and density-based dimensionless variables. 

The next two papers address pipelines. The first paper in this category deals with initial startup velocity in isothermal pipelines with compressible gelled crude oil. It presents efficient numerical formulas to compute startup velocities that facilitate analysis of the safe and economical operation of pipelines transporting waxy oil. The second paper focuses on CO2 erosion-corrosion pipeline failures and presents an empirical model for predicting the erosion-corrosion degradation rate of carbon steel in sand-containing CO2 environments in an offshore facility.

The first paper in the category of production and operations presents a new technique to prepare permeable nonstress-imposing void-free barriers to replace conventional gravel packing for sand control in weakly consolidated sands. The second paper in this category investigates the relative roles of frequencies in electromagnetic steam-assisted-gravity-drainage applications.

The issue continues with two companion papers addressing drilling. Part I presents an exact analytical solution for the flexing and stability of pipe stands in a derrick, and includes a sensitivity analysis with respect to variables such as inclination, material type, and wear. The solution provides useful insights into the stability of unloaded pipe stands racked in a derrick. The second part (Part II) builds on the material presented in Part I, and presents a general pipe-stand model that is based on a Fourier-series solution of the energy equation to simulate a wide range of pipe configurations and loads.

We move on to three papers that address new history-matching methods for reservoir characterization. The first paper presents a new robust history-matching algorithm that uses hybrid parameterization on the basis of geologic (principal-component analysis) and nongeologic (discrete cosine transform) basis functions to describe large-scale connectivity with limited production data and under geologic uncertainty. The second paper presents a new history-matching algorithm for channelized reservoirs on the basis of combining multidimensional scaling with the ensemble Kalman Filter (EnKF) method. The algorithm is useful in creating rapidly-updating models of a channelized reservoir. The last paper in this category also addresses the history matching of channelized reservoirs, but proposes vector-based level-set parameterization methods for history matching of the 2D and 3D channelized-reservoir models. The authors show that these methods can be used with the standard EnKF scheme in the assimilation process.

The last paper in the issue examines estimating the electricity-generating potential of coproduced water from active oil and gas reservoirs. On the basis of a geographic-information system developed with the information from 2.5 million wells, the study finds that the potential is 300 MWe.

In closing, I hope that you enjoy the June issue and its 17 manuscripts. Cheerio and thank you!

Mustafa Onur, Istanbul Technical University