4D reservoir geomechanics: a case study from the HP/HT reservoirs of the Elgin and Franklin fields

Gennaro, S. De; Onaisi, A.; Grandi, A.; Ben-Brahim, L.; Neillo, V.

doi:10.3997/1365-2397.2008019

Cited by 26 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Conventional methodologies employ poststack data and compaction-induced vertical stress/strain to estimate time-lapse velocity and volume changes (Hatchell and Bourne, 2005;Janssen et al, 2006;Carcione et al, 2007;Hodgson et al, 2007;Roste, 2007;Staples et al, 2007;De Gennaro et al, 2008). However, migration and stacking of data represents a complex filtering process that can corrupt phase relationships and arrival times.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of compaction-induced multicomponent seismic time shifts to variations in reservoir properties

Smith

Tsvankin

2013

GEOPHYSICS

View full text Add to dashboard Cite

Pore-pressure variations inside producing reservoirs result in excess stress and strain that influence the arrival times of reflected waves. Inversion of seismic data for pressure changes requires better understanding of the dependence of compactioninduced time shifts on reservoir pressure reduction. Using geomechanical and full-waveform seismic modeling, we investigate pressure-dependent behavior of P-, S-, and PS-wave time shifts from reflectors located above and below a rectangular reservoir embedded in a homogeneous half-space. Our geomechanical modeling algorithm generates the excess stress/strain field and the stress-induced stiffness tensor as linear functions of reservoir pressure. Analysis of time shifts obtained from full-waveform synthetic data shows that they vary almost linearly with pressure for reflectors above the reservoir, but become nonlinear for reflections from the reservoir or deeper interfaces. Time-shift misfit curves computed with respect to noise-contaminated data from a reference reservoir for a wide range of pressure reductions display well-defined global minima corresponding to the actual pressure. In addition, we evaluate the influence of the reservoir width on time shifts and the possibility of constraining the width using time-lapse data. We also discuss the impact of moderate perturbations in the strain-sensitivity coefficients (i.e., third-order stiffnesses) on time shifts and on the accuracy of pressure inversion. Our feasibility analysis indicates that the most stable pressure estimation from noisy data is provided by multicomponent time shifts from reflectors below the reservoir. For multicompartment reservoirs, time shifts can be accurately modeled by linear superposition of the excess stress/strains computed for the individual compartments.

show abstract

Section: Introductionmentioning

confidence: 99%

Sensitivity of compaction-induced multicomponent seismic time shifts to variations in reservoir properties

Smith

Tsvankin

2013

GEOPHYSICS

View full text Add to dashboard Cite

show abstract

“…In recent years, technology advances have enabled applying coupled reservoir geomechanical simulation to investigate how production or injection impacts the mechanical response of a field or a reservoir (Settari and Walters, 2001;Molenaar et al, 2004;Gennaro et al, 2008;Hussein et al, 2010;Qiu et al, 2013). Coupled simulation is either implemented through explicit coupling (or one-way coupling), iterative coupling, or full coupling (Settari and Walters, 2001;Jalali and Dusseault, 2012).…”

Section: D Coupled Geomechanics Simulationmentioning

confidence: 99%

Well Integrity Evaluation for Methane Hydrate Production in the Deepwater Nankai Trough

et al. 2014

View full text Add to dashboard Cite

Large accumulations of methane hydrates are known to exist in the deepwater Nankai Trough located off the southern coast of Japan. Due to its enormous potential as an energy source, there is growing interest in the production of methane gas from these deposits. An offshore production test was scheduled to test the technological viability to produce the methane hydrate by using a depressurization method. However, methane hydrate production may cause large amounts of compaction and subsidence, which can damage well integrity and cause loss of zonal isolation in the overburden. This condition could provide potential leakage pathways for methane gas to the surface and endanger offshore operations.The paper presents a study in which well integrity was evaluated for a methane hydrate production test well in the Nankai Trough. In this study, a new workflow was proposed and applied to honor both fieldwide formation heterogeneity and near-wellbore geometry. The geomechanics properties were determined through integration of seismic inversion data, log data, and core data from the Nankai Trough. Interface elements were installed between the casing and cement and the cement and formation to evaluate the impact of cement bond quality on the well integrity. The numerical simulation was conducted through coupling of the simulation results produced by a methane hydrate production simulator from a third party with a 3D finite-element (FE) geomechanics simulator.The study predicted the occurrence of 2-cm of subsidence on the seafloor generated by approximately 1.5% of reservoir compaction for a production test of 20 days. Over this period, casing would yield with a plastic strain of about 1%. Most findings indicated a low risk in the loss of zonal isolation which is consistent with the results of the production test conducted in March 2013.This simulation evaluated potential risks related to well integrity, and provided critical information for the preparation and execution of the pioneering offshore methane hydrate production test in the Nankai Trough.

show abstract

“…The link between compaction and depletion relates to the understanding of the field geomechanics and the 'arching effect' (De Gennaro et al, 2008). Developing reliable geomechanical models to properly assess the results of the 1 st 4D monitor provided valuable information for HP/HT infill well drilling over Elgin in terms of planning (casing points and mud weight window prediction).…”

Section: Upcoming 4d Time-lapse Seismic Datamentioning

confidence: 99%

West Franklin - How Geophysical Tenacity Led a Modest Franklin Satellite to a Full-Blown Field Development

Patel

Ugolini

Millancourt

et al. 2011

SPE Offshore Europe Oil and Gas Conference and Exhibition

View full text Add to dashboard Cite

The West Franklin HP/HT Field discovered in 2003 by the well 29/5b-F7z was drilled on a simple structure defined using the 1996 Elgin/Franklin 3D seismic -vintage data which has since been superseded by state-of-the-art seismic processing techniques. The original PSTM displayed relatively continuous seismic reflectivity with large uncertainty on imaging and interpretation.The highly productive porous sandstone interval within the Upper Jurassic Fulmar Formation was identified as a high amplitude reflector due to a strong decrease in impedance. Anisotropic PSDM processing followed by an acoustic inversion study highlighted the probable extension of this 'Porous Zone' to the west and underlined the high potential for a second appraisal/development well.Positive results from the second well 29/5b-F9y in 2007 showed dramatic thickening and improvement in reservoir quality to the west and initiated additional PSDM processing of the original 1996 data. Following developments in tomography and migration algorithms, strong imaging improvements were observed from the integrated anisotropic velocity model updates and by reducing the amount of destructive interference from multiples. The resulting interpretation allowed for a better understanding of the salt tectonics and in predicting Fulmar reservoir thickness to the west.A 7km Long Offset 3D survey acquired by CGGV in 2009 with subsequent PSDM processing is bringing further imaging improvements over areas of amplitude degradation leading to potential upsides. A first 4D monitor acquisition over Elgin/Franklin in 2005 (before production had started on West Franklin in 2007) is being followed-up by a second 4D monitor in 2011, aimed at providing additional information on the depletion pattern around the field. Such strategy in ongoing investment in seismic data will further unlock the resource potential over and around West Franklin in the coming years, ensuring a mature area remains in the spotlight.

show abstract

4D reservoir geomechanics: a case study from the HP/HT reservoirs of the Elgin and Franklin fields

Cited by 26 publications

References 0 publications

Sensitivity of compaction-induced multicomponent seismic time shifts to variations in reservoir properties

Sensitivity of compaction-induced multicomponent seismic time shifts to variations in reservoir properties

Well Integrity Evaluation for Methane Hydrate Production in the Deepwater Nankai Trough

West Franklin - How Geophysical Tenacity Led a Modest Franklin Satellite to a Full-Blown Field Development

Contact Info

Product

Resources

About