Joel Walls

Stanford University, Geophysics, Alumnus

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Geophysicist with extensive background in rock properties measurement and reservoir evaluation. Particular focus of last 10 years has been unconventional resources in North and South America and the Middle East.

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Safouh Koronfol

Moustafa Dernaika

University of Stavanger

CSIRO

The Ohio State University

Jeroen Kenter

TOTAL

Geoffrey Thyne

University of Aalborg

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Papers by Joel Walls

North Sea reservoir characterization using rock physics, seismic attributes, and neural networks; a case history

by Joel Walls and Tom Guidish

SEG Technical Program Expanded Abstracts 1999, 1999

A new method was developed to use core, well log, and post-stack seismic data to identify reservo... more A new method was developed to use core, well log, and post-stack seismic data to identify reservoir lithologies between wells. The method was based on a combination of rock physics modeling, seismic attribute generation and pattern recognition via neural network analysis. The result was a new lithologically calibrated attribute that showed the producing wells to be inside the indicated oil sand area and the non-producing wells to be outside this area.

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SPE-172959-MS Petrophysical and Fluid Flow Properties of a Tight Carbonate Source Rock Using Digital Rock Physics

by Joel Walls, Moustafa Dernaika, and Mohammed Zekraoui

The evaluation of shale is complicated by the structurally heterogeneous nature of fine-grained s... more The evaluation of shale is complicated by the structurally heterogeneous nature of fine-grained strata and their intricate pore networks, which are interdependent on many geologic factors including total organic carbon (TOC) content, mineralogy, maturity and grain-size. The ultra-low permeability of the shale rock requires massive hydraulic fracturing to enhance connectivity and increase permeability for the flow. To design an effective fracturing technique, it is necessary to have a good understanding of the reservoir characteristics and fluid flow properties at multiple scales. In this work, representative core plug samples from a tight carbonate source rock in the Middle East were characterized at the core-and pore-scale levels using a Digital Rock Physics (DRP) workflow. The tight nature of the carbonate rocks prevented the use of conventional methods in measuring special core analysis (SCAL) data. Two-dimensional Scanning Electron Microscopy (SEM) and three-dimensional Focused Ion Beam (FIB)-SEM analysis were studied to characterize the organic matter content in the samples together with (organic and inorganic) porosity and matrix permeability. The FIB-SEM images in 3D were also used to determine petrophysical and fluid flow (SCAL) properties in primary drainage and imbibition modes. A clear trend was observed between porosity and permeability related to identified rock fabrics and organic matter in the core. The organic matter was found to have an effect on the imbibition two-phase flow relative permeability and capillary pressure behavior and hysteresis trends among the analyzed samples. The data obtained from DRP provided information that can enhance the understanding of the pore systems and fluid flow properties in tight formations, which cannot be derived accurately using conventional methods. Introduction Unconventional shale reservoirs differ largely from conventional sandstone and carbonate reservoirs in their origin, geologic evolution and current occurrence. Shale comprises a variety of rocks that are composed of extremely fine-grained particles with very low porosity and permeability values in the order of few porosity units and nano-darcy range, respectively. Shale formations are very complex at the core scale, and exhibit large vertical variations in lithology and Total Organic Carbon (TOC) at a small scale that renders core characterization and sweet spot detection very challenging. Shale formations are also very complex at the nano-scale where the pores have different porosity types that are detected within kerogen and rock matrix.

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Pulse Decay Permeability: Analytical Solution and Experimental Test

Society of Petroleum Engineers Journal, 1982

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Effects of pore fluid properties at high pressure and temperature on seismic response

SEG Technical Program Expanded Abstracts 2005, 2005

Tight Gas Sands-Permeability, Pore Structure, and Clay

Journal of Petroleum Technology, 1982

Gas permeability has been measured on a suite of cores from the Spirit River tight gas sand of we... more Gas permeability has been measured on a suite of cores from the Spirit River tight gas sand of western Alberta and on two samples from the Cotton Valley formation of east Texas. Using nitrogen as the mobile fluid, we have measured permeability as a function of partial water saturation at in-situ levels of pore pressure and confining pressure. Samples from both locations show strong dependence of permeability (k) on effective pressure and on the degree of water or brine saturation. The validity of Darcy's law in the microdarcy range has been verified in a dry Spirit River sample. Extensive thin-section, x-ray diffraction, and scanning electron microscope (SEM) studies have been conducted. The primary clays in Spirit River and Cotton Valley cores are chlorite and illite. In one sample we measured k vs. saturation first with distilled water and then with a 2% KCl brine solution and saw no significant change in permeability behavior. By observing the effects of pressure, partial saturation, and salinity on permeability in these samples, we can deduce several important characteristics of the pore structure and can evaluate the relative importance of clay content.

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Measurement of Fluid Salinity Effects on Tight Gas Sands With a Computer Controlled Permeameter

SPE Annual Technical Conference and Exhibition, 1982

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Fluids, AVO, and seismic amplitudes: Field examples

SEG Technical Program Expanded Abstracts 1996, 1996

In situ stress azimuth and magnitude from well log measurements. Final report, May 1993-May 1995

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Propiedades del reservorio de arcillas de Eagle Ford a partir de física digital de rocas

First Break, Jun 1, 2011

A rock physics and attenuation analysis of a well from the Gulf of Mexico

SEG Technical Program Expanded Abstracts 2005, 2005

Quantifying Variability of Reservoir Properties From a Wolfcamp Formation Core

Proceedings of the 3rd Unconventional Resources Technology Conference, 2015

Seismic wave attenuation at full water saturation

SEG Technical Program Expanded Abstracts 2003, 2003

Rock property determination using digital rock physics

by Joel Walls and Manika Prasad

The Digital Rock Physics (DRP) technology is based on a rigorous numerical simulation of physical... more The Digital Rock Physics (DRP) technology is based on a rigorous numerical simulation of physical experiments in a realistic pore space, at the pore-scale level. DRP complements lab measurements and, at the same time, enormously enhances the geoscientist's capabilities because digital experiments can be conducted in real time and on small fragments of rock, such as drill cuttings. We report a feasibility study on DRP technology applied to drill cutting samples to obtain porosity, permeability, and the P-and S-wave velocity.

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Seismic and EM rock physics and modeling, Norwegian Sea

SEG Technical Program Expanded Abstracts 2008, 2008

A theoretical estimate of S‐wave attenuation in sediment

SEG Technical Program Expanded Abstracts 2005, 2005

ABSTRACT

Use of Compressional and Shear Wave Velocity for Overpressure Detection

Offshore Technology Conference, 2000

... Page 2. 2 JOEL WALLS, JACK DVORKIN, GARY MAVKO, AND AMOS NUR, ROCK SOLID IMAGES, HOUSTON, TX ... more

Shale Reservoir Evaluation Improved by Dual Energy X-Ray CT Imaging

Journal of Petroleum Technology, 2012

Reservoir Characterisation Through Joint Interpretation of CSEM, Seismic and Well Data