Integrated Time-Lapse Rock Physics Measurements – the Key to Understanding Reservoir Elastic Moduli Changes with Hydrocarbon Production

2000 ◽  
Author(s):  
R.B Guerra ◽  
J.H. Meyer ◽  
A.M. Sibbit ◽  
R. Van Delden
Keyword(s):  
Elastic Moduli ◽  
Rock Physics ◽  
Time Lapse ◽  
Hydrocarbon Production

ROCK PHYSICS—APPLICATION TO GEOLOGICAL STORAGE OF CO2

2003 ◽  
Vol 43 (1) ◽  
pp. 567 ◽  
Author(s):  
J.J. McKenna ◽  
B. Gurevich ◽  
M. Urosevic ◽  
B.J. Evans
Keyword(s):  
Elastic Moduli ◽  
Co2 Storage ◽  
Rock Physics ◽  
Sedimentary Basins ◽  
Time Lapse ◽  
Seismic Monitoring ◽  
Potential Contribution ◽  
Underground Brine ◽  
Shear Moduli ◽  
Borehole Seismic

Sequestration of anthropogenic CO2 into underground brine-saturated reservoirs is an immediate option for Australia to reduce CO2 emissions into the atmosphere. Many sites for CO2 storage have been defined within many Australian sedimentary basins. It is anticipated that seismic technology will form the foundation for monitoring CO2 storage within the subsurface, although it is recognised that several other technologies will also be used in support of seismic or in situations where seismic recording is not suitable. The success of seismic monitoring will be determined by the magnitude of the change in the elastic properties of the reservoir during the lifecycle of CO2 storage. In the short-term, there will be a strong contrast in density and compressibility between free CO2 and brine. The contrast between these fluids is greater at shallower depth and higher temperature where CO2 resembles a vapour. The significant change in the elastic moduli of the reservoir will enable time-lapse seismic methods to readily monitor structural or hydrodynamic trapping of CO2 below an impermeable seal. Because the acoustic contrast between brine saturated with CO2 and brine containing no dissolved CO2 is very slight, however, dissolved CO2 is unlikely to be detected by any seismic technology, including high-resolution borehole seismic. The detection of increases in porosity, associated with dissolution of susceptible minerals within the reservoir may provide a means for qualitative monitoring of CO2 dissolution. Conversion of aqueous CO2 into carbonate minerals should cause a detectable rise in the elastic moduli of the rock frame, especially the shear moduli. The magnitude of this rise increases with depth and demonstrates the potential contribution that can be made from repeated shear-wave and multi-component seismic measurements. Forward modelling suggests that the optimal reservoir depth for seismic monitoring of CO2 storage within an unconsolidated reservoir is between 1,000 and 2,500 m. Higher reservoir temperature is also preferred so that free CO2 will resemble a vapour.

scholarly journals Influence of microheterogeneity on effective stress law for elastic properties of rocks

Geophysics ◽  
2008 ◽  
Vol 73 (1) ◽  
pp. E7-E14 ◽  
Author(s):  
Radim Ciz ◽  
Anthony F. Siggins ◽  
Boris Gurevich ◽  
Jack Dvorkin
Keyword(s):  
Effective Stress ◽  
Seismic Data ◽  
Elastic Moduli ◽  
Seismic Velocity ◽  
Time Lapse ◽  
Seismic Velocities ◽  
Laboratory Measurements ◽  
Hydrocarbon Production ◽  
Stress Coefficient ◽  
Seismic Measurements

Understanding the effective stress coefficient for seismic velocity is important for geophysical applications such as overpressure prediction from seismic data as well as for hydrocarbon production and monitoring using time-lapse seismic measurements. This quantity is still not completely understood. Laboratory measurements show that the seismic velocities as a function of effective stress yield effective stress coefficients less than one and usually vary between 0.5 and 1. At the same time, theoretical analysis shows that for an idealized monomineral rock, the effective stress coefficient for elastic moduli (and therefore also for seismic velocities) will always equal one. We explore whether this deviation of the effective stress coefficient from unity can be caused by the spatial microheterogeneity of the rock. The results show that only a small amount (less than 1%) of a very soft component is sufficient to cause this effect. Such soft material may be present in grain contact areas of many rocks and may explain the variation observed experimentally.

Compaction-induced anisotropy and time-lapse AVO analysis

2015 ◽  
Vol 3 (2) ◽  
pp. SP21-SP33 ◽  
Author(s):  
Nayyer Islam ◽  
Wayne D. Pennington
Keyword(s):  
Elastic Moduli ◽  
Rock Physics ◽  
Time Lapse ◽  
Pressure Effects ◽  
Reservoir Pressure ◽  
Pressure Sensitivity ◽  
Induced Anisotropy ◽  
Amplitude Variation ◽  
Amplitude Variation With Offset ◽  
Sandstone Reservoir

Hydrocarbon reservoirs are often monitored using repeated seismic observations to track fluid movement and other changes. Here, we present a study of compaction-induced anisotropy in an unconsolidated overpressured sandstone reservoir from Teal South field in the Gulf of Mexico. Previous work at Teal South had demonstrated that the time-lapse observations could not be satisfied through models of fluid changes without strong pressure effects acting on the formation rock framework. However, those studies are not highly quantitative, and some minor inconsistencies appear on closer examination. We have examined the effect of the pressure-sensitivity of elastic moduli in the formation and carefully examined the offset-dependence of amplitudes in light of several rock-physics models, empirical and theoretical. The amplitude-variation-with-offset behavior for the interface between overlying shale and the hydrocarbon sand is best modeled under the assumption that this overpressured reservoir becomes anisotropic because it undergoes compaction during production, which reduces the reservoir pressure from highly overpressured to nearly normal for this depth. Although the results obtained here are only weakly constrained due to the limited offset ranges and low fold, this strongly suggests that anisotropic effects in poorly consolidated overpressured reservoirs undergoing primary depletion may in fact dominate over fluid effects after the bubble point has been reached.

scholarly journals Time-lapse rock-physics inversion of thermal heavy oil production

2017 ◽  
Author(s):  
Evan Mutual ◽  
David Cho ◽  
Kristopher Albert Innanen
Keyword(s):  
Heavy Oil ◽  
Rock Physics ◽  
Oil Production ◽  
Time Lapse

scholarly journals Time-Lapse Seismic Monitoring of Onshore Reservoirs in Niger Delta, Field ‘K’ as a Case Study

2017 ◽  
Vol 1 (1) ◽  
pp. 23-27 ◽  
Author(s):  
A. Ogbamikhumi ◽  
T. Tralagba ◽  
E. E. Osagiede
Keyword(s):  
Seismic Data ◽  
Acoustic Impedance ◽  
Niger Delta ◽  
Rock Physics ◽  
Time Lapse ◽  
Seismic Survey ◽  
Impedance Change ◽  
Data Set ◽  
Reservoir Fluid ◽  
4D Seismic

Field ‘K’ is a mature field in the coastal swamp onshore Niger delta, which has been producing since 1960. As a huge producing field with some potential for further sustainable production, field monitoring is therefore important in the identification of areas of unproduced hydrocarbon. This can be achieved by comparing production data with the corresponding changes in acoustic impedance observed in the maps generated from base survey (initial 3D seismic) and monitor seismic survey (4D seismic) across the field. This will enable the 4D seismic data set to be used for mapping reservoir details such as advancing water front and un-swept zones. The availability of good quality onshore time-lapse seismic data for Field ‘K’ acquired in 1987 and 2002 provided the opportunity to evaluate the effect of changes in reservoir fluid saturations on time-lapse amplitudes. Rock physics modelling and fluid substitution studies on well logs were carried out, and acoustic impedance change in the reservoir was estimated to be in the range of 0.25% to about 8%. Changes in reservoir fluid saturations were confirmed with time-lapse amplitudes within the crest area of the reservoir structure where reservoir porosity is 0.25%. In this paper, we demonstrated the use of repeat Seismic to delineate swept zones and areas hit with water override in a producing onshore reservoir.

Common-focus point-based target-oriented imaging approach for continuous seismic reservoir monitoring

Geophysics ◽  
2018 ◽  
Vol 83 (4) ◽  
pp. M41-M48 ◽  
Author(s):  
Hongwei Liu ◽  
Mustafa Naser Al-Ali
Keyword(s):  
Seismic Data ◽  
Rock Physics ◽  
Time Lapse ◽  
Velocity Estimation ◽  
Estimation Methods ◽  
Data Sets ◽  
Data Set ◽  
Velocity Models ◽  
Reservoir Monitoring ◽  
Focus Point

The ideal approach for continuous reservoir monitoring allows generation of fast and accurate images to cope with the massive data sets acquired for such a task. Conventionally, rigorous depth-oriented velocity-estimation methods are performed to produce sufficiently accurate velocity models. Unlike the traditional way, the target-oriented imaging technology based on the common-focus point (CFP) theory can be an alternative for continuous reservoir monitoring. The solution is based on a robust data-driven iterative operator updating strategy without deriving a detailed velocity model. The same focusing operator is applied on successive 3D seismic data sets for the first time to generate efficient and accurate 4D target-oriented seismic stacked images from time-lapse field seismic data sets acquired in a [Formula: see text] injection project in Saudi Arabia. Using the focusing operator, target-oriented prestack angle domain common-image gathers (ADCIGs) could be derived to perform amplitude-versus-angle analysis. To preserve the amplitude information in the ADCIGs, an amplitude-balancing factor is applied by embedding a synthetic data set using the real acquisition geometry to remove the geometry imprint artifact. Applying the CFP-based target-oriented imaging to time-lapse data sets revealed changes at the reservoir level in the poststack and prestack time-lapse signals, which is consistent with the [Formula: see text] injection history and rock physics.

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