Characterization of a steamed oil reservoir using cross‐well seismology

Paulsson, Björn; Smith, M. Elliot; Tucker, Karla E.; Fairborn, John W.

doi:10.1190/1.1436885

Cited by 13 publications

(7 citation statements)

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“…Seimic tomography has been very succesful in monitoring EOR produced changes with respect to time. Excellent examples of the seismic mapping of steam injection and in-situ combustion processes can be found in Bregman, et al (1989), Justice, et al (1989) and Paulsson, et al (1992). Cross-well resistivity tomography has shown promise in monitoring both oil and environmental related steam injections (Beasley and Tripp, 199 1, Shima and Imamura, 199 1, Ramirez, et al, 1992) and Daily and Ramirez (1992) have found it useful for tracking the flow of ground water through the unsaturated zone.…”

Section: Geophysical Methods For Reservoir Process Monitoringmentioning

confidence: 99%

Iterative electromagnetic Born inversion applied to earth conductivity imaging

Alumbaugh¹

1993

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order Born approximation is applied to linearize the integral equations. From these simplified equations, sensitivity functions are derived which define the ability of the crosswell magnetic field measurements to detect small local changes in conductivity. Plots of the spatial variation in sensitivity indicate that vertical resolution is a function of the spatial sampling density in the vertical direction, while the horizontal resolution depends on the vertical separation between the source and receiver. Additional improvement in the horizontal resolution can be provided by making additional measurements with both the source and receiver in the same hole.Further sensitivity analysis is completed in terms of a dimensionless background induction number that is defined by oopl2 where o is the background conductivity and 1 is the source-receiver separation. Analysis of the crosswell sensitivity in terms of this parameter facilitates experimental system design for a given borehole separation and background conductivity, as well as the determination of the operating frequency which falls within an optimal range of oo@ 2.For oopl2 ~1 0 , the scattered fields are very small compared to the primary field, making measurements of the inhomogenous response very difficult in the presence of noise. In addition, a given source-receiver pair is sensitive to a large volume of strata outside of the interwell zone rather than just the region immediately between the probes. The latter property requires that a larger region be considered in the interpretation phase and that the proper 2-D or 3-D model geometry is employed. As the induction number is increased the nature of the sensitivity functions change. For oopl2 > 50 a given source-receiver pair is sensitive only to a "ray-path" shaped zone immediately between the two probes and the scattered fields are on the same order of magnitude as the primary fields. Unfortunately the attenuation at these large induction numbers prevents accurate measurement of the fields for large vertical probe separation due to the dynamic range limitations of the measurement system.The validity of using a 2-D cylindrical model to simulate a generally inhomogenous earth is investigated by comparing the 2-D Born series solution to other 1-D, 2-D and 3-D modeling algorithms. For ooyl2 < 50 the size of the region outside of the wells that is included in the model has a significant effect on the properties of the calculated EM fields with the different model geometries producing significantly different results. At larger induction numbers (owpl2 >50) a given source-receiver pair senses only the medium directly between the probes and the resulting fields are fairly independent of whether a 1-D, 2-D or 3-D model is employed. Unfortunately at these large induction numbers the Born series does not readily converge.To image the subsurface conductivity smcture between two wells, the 2-D cylindrical Born series approximation is incorporated into an iterative Born inversion scheme. The inversion problem is stabiliz...

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Section: Geophysical Methods For Reservoir Process Monitoringmentioning

confidence: 99%

Iterative electromagnetic Born inversion applied to earth conductivity imaging

Alumbaugh¹

1993

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“…New, high precision three-dimensional (3-D) seismic techniques respond to remarkably local variations in rock properties (Robertson, 1989;Johnston, 1989;Abriel et al, 1991;Metrailer, 1991). Crosswell ultraseismic arrays attempt to monitor fluid flow within reservoirs (Paulsson et al, 1992). Using a dipole source (Harrison et al, 1990), sonic shear slowness can now be measured in a borehole for all formations.…”

Section: Introductionmentioning

confidence: 99%

Modulus decomposition of compressional and shear velocities in sand bodies

Murphy

Reischer

Hsu³

1993

GEOPHYSICS

153

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The advent of borehole shear slowness measurements in sonically slow formations has lead to breakthroughs in the subsurface profiling of geological bodies. In sand bodies, compressional and shear velocities depend predictably on porosity, mineralogy, grain contacts, and fluid saturation. An interpretation is best performed by decomposing the velocities into moduli that are intrinsic measures of the rock frame and pore fluid compressibilities. Careful experiments on pure materials (i.e., pure quartz sandstones) demonstrate two simplifying constitutive relationships. First, the bulk and shear frame moduli are simple functions of the porosity. A comparison of the measured shear frame modulus to the prediction for the pure material INTRODUCTION

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“…It is noted that the use of time-lapse seismic technology for reservoir monitoring has found widespread application, within the last 10-15 years, for various reservoir processes, including those involved steam injection [10][11][12]. In these cases, analysis of the time-lapse seismic results has enabled an understanding of steam chamber growth (or lack of) and/or steam conformance along the wellbore, leading to remedial actions.…”

Section: Reservoir Background and Sagd Processmentioning

confidence: 99%

Understanding Reservoir Architectures and Steam Chamber Growth at Christina Lake, Alberta, by Using 4D Seismic and Crosswell Seismic Imaging

Zhang¹,

Youn

Doan

2005

Proceedings of SPE/PS-CIM/CHOA International Thermal Operations and Heavy Oil Symposium

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The Christina Lake Thermal Project, located 170 km South of Fort McMurray, Alberta, uses steam-assisted gravity drainage (SAGD) technology to recover bitumen from the McMurray formation. The bitumen reservoir at Christina Lake is approximately 400m deep, and is delineated by over 300 vertical wells and extensive 3D seismic coverage. The McMurray formation can be informally subdivided into three units -Lower, Middle and Upper. The Middle unit contains the major bitumen bearing reservoir, while the Lower unit is generally water bearing and the Upper unit typically contains gas with some residual bitumen saturation. SAGD at Christina Lake was first implemented in 2001 (Phase 1, Figure 1). The currently developed project area is covered by time-lapse surface 3D seismic and crosswell seismic.The 3D survey was acquired using mega-bin geometry, with a bin size of 12.5 m by 12.5 m. A baseline survey was conducted in 2001 followed by two repeat surveys in 2004 and 2005. In addition, six crosswell seismic profiles were acquired by placing both sources and receivers in vertical wellbores. The goal of the survey is to better understand reservoir architecture by detecting lithology changes, including predicting the occurrence of mudstone stringers and their lateral and vertical distribution. Crosswell seismic data in this project have provided about one metre vertical resolution in the McMurray Formation, detected mudstone stringers, and indicated significant reservoir heterogeneity, all of which helped to more accurately characterize the reservoir and better predict reservoir performance under thermal operations. Results of the six profiles provide encouraging insight into the potential of crosswell seismic technology. Although there is a need for future research in several areas, crosswell seismic has the potential to complement and enhance the interpretation of surface 3D seismic.Analysis of both 4D and crosswell data showed that steam chamber growth and oil recovery are strongly influenced by reservoir geology. Steam chamber growth is especially affected by the presence of low permeability facies in the vicinity of the SAGD well pairs. In each case to date, less than 100% of the well length contributes to oil production. These findings have significant impacts on the planning of future developments.

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Characterization of a steamed oil reservoir using cross‐well seismology

Cited by 13 publications

References 0 publications

Iterative electromagnetic Born inversion applied to earth conductivity imaging

Iterative electromagnetic Born inversion applied to earth conductivity imaging

Modulus decomposition of compressional and shear velocities in sand bodies

Understanding Reservoir Architectures and Steam Chamber Growth at Christina Lake, Alberta, by Using 4D Seismic and Crosswell Seismic Imaging

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