Executive Summary

This month, we bring you 20 papers organized under five categories.

Flow in Pipes and Drilling. Helgaker et al. report a large-scale sand-erosion test of an unbonded flexible pipe. At some locations, measured erosion was 30 to 40% higher than predicted by industry-standard methods.

Shimizu et al. performed experiments in a flow loop to characterize flow of methane hydrates in pipes. Six classifications of multiphase flow patterns were identified and discussed in relation to flow assurance.

Gao et al. provide a wellbore/formation-coupled heat transfer model to predict dissociation of hydrates during deepwater drilling. The risk of hydrate dissociation increases with increased drilling-fluid-injection temperature, increased flow rate, and increased circulation time.

Kullawan et al. examine how sequential geosteering decisions can be optimized using discetized-stochastic-dynamic programming. Effective use of the process requires accurate look-ahead measurements and the flexibility to rapidly make large directional changes.

PVT and Phase Behavior. Zheng and Yang used dynamic volume analysis to determine individual diffusion coefficients of propane/butane/CO2/heavy-oil systems at high pressures and elevated temperatures. The alkane solvents were found to diffuse faster than CO2 in heavy oil and also promoted mass transfer and swelling.

Goel et al. used computational-intelligence-based models to predict °API values for crude oil using SARA (saturates, aromatics, resins, and asphaltene) fractions as input. Data from 403 crude oils were used to develop the nonlinear correlations.
Bui and Akkutlu use molecular Monte Carlo simulations to demonstrate that small hydrocarbon molecules escape more readily from small pores (< 10 nm), resulting in a progressive concentration of viscous heavy hydrocarbons in nanopores during depletion processes.

Saboorian-Jooybari and Pourafshary develop an analytical method (based on infiltration theory) to predict phase trapping in reservoirs. The new method allows for time-dependence and is applicable to any range of rock and fluid properties. An example application in a tight gas reservoir is presented.

Oilfield Chemistry. Reid et al. used powder X-ray diffraction and X-ray absorption near-edge structure spectroscopy to analyze a toluene-insoluble residue from an alkaline/surfactant/polymer flood in Taber, Alberta. The methods identified the residue as heulandite (a complex zeolite) and suggested that a corrosion inhibitor played a role in the residue formation, rather than the hydrolyzed polyacrylamide polymer used.

Zhang et al. consider scale risk and scale inhibition for a steamflood pilot project in a dolomite formation with interbedded anhydrite. A predictive model and treatment program were developed to effectively control anhydrite scale in the field.

Dong et al. developed a model to predict wormhole growth during carbonate matrix acidizing. The model predicts optimum acid injection rate, accounting for rock lithology, acid concentration, temperature, and rock-pore-size distribution.

Improved Oil Recovery. Heidari et al. use a semi-analytical model to investigate how temperature-dependent thermal conductivity, heat capacity, and rock density affect the performance of SAGD. The model is aimed to provide a tool for quick evaluations of SAGD processes.

Bourbiaux et al. used computed tomography scanning to monitor foam flow in fractured carbonate cores. Foams in fractures promoted entry of wettability modifiers into the rock matrix, thereby aiding oil recovery.

He et al. present a semi-analytical methodology of pressure-transient analysis to diagnose the locations of underperforming hydraulic fractures in tight gas reservoirs. The method is applied to a field case to illustrate its physical consistency and practicality.

Improving Reservoir Simulation. Boek et al. present an overview of recent developments of lattice Boltzmann and particle-tracing simulations to study flow and reactive transport in porous media. Several applications are covered to demonstrate their utility, including capillary pressure and relative permeability calculations, multiphase flow of immiscible and partially miscible fluids (e.g., CO 2/brine mixtures), matrix acidizing, and carbon-capture and storage.

Zidane and Firoozabadi applied fracture-cross-flow equilibrium to simulate two-phase flow in fractured porous media. Complexities arising from upstreaming of concentration derivatives and countercurrent gravity flow are overcome using an upstreaming technique at the fracture/fracture interface and the matrix/fracture interface.

Zhang et al. propose a damped iterative-ensemble-Kalman-filter algorithm to estimate relative permeability and capillary pressure curves simultaneously for a test reservoir model (i.e., the PUNQ-S3 model).

Luo et al. propose a 4D-seismic history-matching framework for reservoir characterization. The process adopts wavelet-based sparse representation to reduce data size. It uses intercept and gradient attributes derived from amplitude vs. angle data, applies multilevel discrete wavelet transforms to attribute data, and estimates noise levels of resulting wavelet coefficients. Wavelet coefficients are selected above a threshold level, and leading wavelet coefficients are history matched with an iterative ensemble smoother.  

Randy Seright,  SPE J. Executive Editor;
New Mexico Institute of Mining and Technology