Modeling of Reservoir Compaction and Surface Subsidence at South Belridge

Hansen, Kirk S.; Prats, M.; Chan, C. K.

doi:10.2118/26074-pa

Cited by 17 publications

(15 citation statements)

References 9 publications

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“…For example, there is little correlation between shear failure in wells and their position with respect to the outer edge of the field, where the large scale and long term horizontal shear stress is often the greatest. This was also the case for the South Belridge Field to the north, where it was observed that well failures occurred throughout the area of production rather than simply along the perimeter or within the centre of the zone of subsidence (Hansen et al 1995;Myer et al 1996;Fredrich et al 2000). Furthermore, an analysis of the spatial distribution of well failures at the South Belridge field, obtained from a comprehensive database, indicates that well damage is influenced by local patterns of injection and production .…”

Section: Discussionmentioning

confidence: 79%

Estimating fluid-induced stress change from observed deformation

Vasco¹,

Harness²,

Pride³

et al. 2016

Geophys. J. Int.

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S U M M A R YObserved deformation is sensitive to a changing stress field within the Earth. However, there are several impediments to a direct inversion of geodetic measurements for changes in stress. Estimating six independent components of stress change from a smaller number of displacement or strain components is inherently non-unique. The reliance upon surface measurements leads to a loss of resolution, due to the attenuation of higher spatial frequencies in the displacement field with distance from a source. We adopt a technique suited to the estimation of stress changes due to the injection and/or withdrawal of fluids at depth. In this approach the surface displacement data provides an estimate of the volume change responsible for the deformation, rather than stress changes themselves. The inversion for volume change is constrained by the fluid fluxes into and out of the reservoir. The distribution of volume change is used to calculate the displacements in the region above the reservoir. Estimates of stress change follow from differentiating the displacement field in conjunction with a geomechanical model of the overburden. We apply the technique to Interferometric Synthetic Aperture Radar (InSAR) observations gathered over a petroleum reservoir in the San Joaquin Valley of California. An analysis of the InSAR range changes reveals that the stress field in the overburden varies rapidly both in space and in time. The inferred stress variations are found to be compatible with the documented failure of a well in the field.

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Section: Discussionmentioning

confidence: 79%

Estimating fluid-induced stress change from observed deformation

Vasco¹,

Harness²,

Pride³

et al. 2016

Geophys. J. Int.

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“…The geomechanical finite element simulations of reservoir compaction and surface subsidence at the Belridge Diatomite Field (e.g., Hansen et al, 1995;de Rouffignac et al, 1995;Fredrich et al, 1996Fredrich et al, , 1998 depend fundamentally on: (1) the mechanical loading, which is a direct function of the reservoir pressure history as derived from two-and three-dimensional reservoir simulations; and (2) the material model and constitutive parameters of the reservoir and overburden rock.…”

Section: Resultsmentioning

confidence: 99%

Estimation of constitutive parameters for the Belridge Diatomite, South Belridge Diatomite Field

Fossum¹,

Fredrich²

1998

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“…The initial stress state & time zero was prescribed following Hansen et alg The vertical (total) principal stress due to gravitational loading was calculated directly on an element by element basis from the bulk density of the overlying materials with initial pore pressures in the different stratigraphic layers calculated as described in Ref. 9. The two effective horizontal principal stresses, that are initially oriented parallel to the model boundaries, were calculated for each element by multiplying the effective vertical stress previously computed by factors of 0.65 and 1.20.…”

Section: Contactmentioning

confidence: 99%

“…The two effective horizontal principal stresses, that are initially oriented parallel to the model boundaries, were calculated for each element by multiplying the effective vertical stress previously computed by factors of 0.65 and 1.20. 9 The model's response to the application of the in siru stresses (referred to as the geostatic step) serves as a quality check. Large inelastic deformations and/or the appearance of shear components in the stress tensor may indicate that the imposed initial stress state is not consistent with the geomechanical model.…”

Section: Contactmentioning

confidence: 99%

Geomechanical Modeling of Reservoir Compaction, Surface Subsidence, and Casing Damage at the Belridge Diatomite Field

Fredrich

Argüello

Deitrick

et al. 2000

SPE Reservoir Evaluation &Amp; Engineering

105

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Summary Geologic, and historical well failure, production, and injection data were analyzed to guide development of three-dimensional geomechanical models of the Belridge diatomite field, California. The central premise of the numerical simulations is that spatial gradients in pore pressure induced by production and injection in a low permeability reservoir may perturb the local stresses and cause subsurface deformation sufficient to result in well failure. Time-dependent reservoir pressure fields that were calculated from three-dimensional black oil reservoir simulations were coupled unidirectionally to three-dimensional nonlinear finite element geomechanical simulations. The reservoir models included nearly 100,000 gridblocks (100 to 200 wells), and covered nearly 20 years of production and injection. The geomechanical models were meshed from structure maps and contained more than 300,000 nodal points. Shear strain localization along weak bedding planes that causes casing doglegs in the field was accommodated in the model by contact surfaces located immediately above the reservoir and at two locations in the overburden. The geomechanical simulations are validated by comparison of the predicted surface subsidence with field measurements, and by comparison of predicted deformation with observed casing damage. Additionally, simulations performed for two independently developed areas at South Belridge, Secs. 33 and 29, corroborate their different well failure histories. The simulations suggest the three types of casing damage observed, and show that, although water injection has mitigated surface subsidence, it can, under some circumstances, increase the lateral gradients in effective stress that in turn can accelerate subsurface horizontal motions. Geomechanical simulation is an important reservoir management tool that can be used to identify optimal operating policies to mitigate casing damage for existing field developments, and applied to incorporate the effect of well failure potential in economic analyses of alternative infilling and development options. Introduction Well casing damage induced by formation compaction has occurred in reservoirs in the North Sea, the Gulf of Mexico, California, South America, and Asia.1–4 As production draws down reservoir pressure, the weight of the overlying formations is increasingly supported by the solid rock matrix that compacts in response to the increased stress. The diatomite reservoirs of Kern County, California, are particularly susceptible to depletion-induced compaction because of the high porosity (45 to 70%) and resulting high compressibility of the reservoir rock. At the Belridge diatomite field, located ~45 miles west of Bakersfield, California, nearly 1,000 wells have experienced severe casing damage during the past ~20 years of increased production. The thickness (more than 1,000 feet), high porosity, and moderate oil saturation of the diatomite reservoir translate into huge reserves. Approximately 2 billion bbl of original oil in place (OOIP) are contained in the diatomite reservoir and more than 1 billion bbl additional OOIP is estimated for the overlying Tulare sands. The Tulare is produced using thermal methods and accounts for three-quarters of the more than 1 billion bbl produced to date at Belridge.5 Production from the diatomite reservoir is hampered by the unusually low matrix permeability (typically ranging from 0.1 to several md), and became economical only with the introduction of hydraulic fracturing stimulation techniques in the 1970's.6 However, increased production decreased reservoir pressure, accelerated surface subsidence, and increased the number of costly well failures in the 1980's. Waterflood programs were initiated in the late 1980's to combat the reduced well productivity, accelerated surface subsidence, and subsidence-induced well failure risks. Subsidence rates are now near zero; however, the well failure rate, although lower than that experienced in the 1980's, is still economically significant at 2 to 6% of active wells per year. In 1994 a cooperative research program was undertaken to improve understanding of the geomechanical processes causing well casing damage during production from weak, compactable formations. A comprehensive database, consisting of historical well failure, production, injection, and subsidence data, was compiled to provide a unique, complete picture of the reservoir and overburden behavior.7,8 Analyses of the field-wide database indicated that two-dimensional approximations9–11 could not capture the locally complex production, injection, and subsidence patterns, and motivated large-scale, three-dimensional geomechanical simulations. Intermediary results for Sec. 33 that used preliminary reservoir flow and material models were reported earlier.8 This paper presents results for best-and-final simulations that used improved reservoir flow models, more sophisticated material models, and activated contact surfaces. The simulations were performed for two independently developed areas at South Belridge, Secs. 33 and 29.

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Modeling of Reservoir Compaction and Surface Subsidence at South Belridge

Cited by 17 publications

References 9 publications

Estimating fluid-induced stress change from observed deformation

Estimating fluid-induced stress change from observed deformation

Estimation of constitutive parameters for the Belridge Diatomite, South Belridge Diatomite Field

Geomechanical Modeling of Reservoir Compaction, Surface Subsidence, and Casing Damage at the Belridge Diatomite Field

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