Effect of temperature on wave velocities in sands and sandstones with heavy hydrocarbons

Wang, Zhijing; Nur, Amos

doi:10.1190/1.1893070

Cited by 20 publications

(30 citation statements)

References 3 publications

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“…In this section, we discuss the influence of various factors-such as porosity, saturation, temperature, and pressure-on the velocities in rocks with CO 2 and hydrocarbons. (2) where K and G=bulk and shear moduli, respectively, and p = density of the material. The Gassmann 8 equation relates the bulk modulus of the saturated rock to the properties of the rock and the pore fluid: When a rock sample is partially liquid-saturated, the bulk modulus of the rock is about the same as that of dry rock, but the overall density is highcr, so v p can bc even lower than in dry (gassaturated) rock.…”

Section: Discussionmentioning

confidence: 99%

“…At higher pore pressures, higher Vs in the hydrocarbon-saturated samples is caused by the higher viscosity and lower density of the C 16H34 in the rock pores. 2 Upon CO 2 injection, the hydrocarbon-bearing rock sample is partially saturated with CO 2 with compressibility close to air. Therefore, the effect of CO 2 injection on the compressional velocities should be close to that of partial gas saturation, which depends on the porosity of the rocks.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, high crack content of the rock and high viscosity of the pore fluid may increase the shear modulus of the saturated rock, which contributes to both vp and vs. 2 The unconsolidated dry Ottawa sand is highly compressible (low compressional velocity) compared with the consolidated sandstones. Liquid saturation will greatly increase its bulk modulus and hence vp (Eq.…”

Section: Discussionmentioning

confidence: 99%

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Effects of CO2 Flooding on Wave Velocities in Rocks With Hydrocarbons

Wang¹,

Nur²

1989

SPE Reservoir Engineering

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Compressional-and shear-wave velocities were measured in the laboratory in seven sandstones (porosities ranging from 6 to 29%) and one unconsolidated sand (37% porosity) saturated with n-hexadecane (C 16H34) both before and after CO 2 flooding. CO 2 flooding decreased compressional-wave velocities significantly, while shear-wave velocities were less affected. The magnitude of these effects was found to depend on confining and pore pressures, temperature, and porosities of the rocks. The experimental results and theoretical analysis show that the decreases in compressional-wave velocities caused by CO 2 flooding may be seismically resolvable in situ. Therefore, seismic-especially high-frequency, high-resolution seismic-methods may be useful in mapping and locating CO 2 zones, tracking movements of CO 2 fronts, and monitoring flooding processes in reservoirs undergoing CO 2 flooding. IntroductionOn average, nearly three-quarters of the hydrocarbons in place are not recoverable by conventional methods. Developments in new EOR methods are therefore becoming more and more important to scientists and engineers. One EOR method uses high-pressure CO 2 injection to recover oils left behind by conventional recovery from reservoir rocks. Of course, not all reservoirs are suitable for CO 2 floodings or for other EOR methods, but considerable effort is currently being made in the oil industry to implement large-scale CO 2 injection projects, in addition to relatively smaller ongoing CO 2 injection pilots. I With development of better EOR methods, methods of monitoring EOR processes are also becoming important because monitoring will open the door for control and modification of recovery processes. In our view, seismic methods are among the more promising monitoring methods. Seismic field survey is relatively economical, and the acquisition and processing of field data are fairly routine. Furthermore, seismic monitoring does not generally require shutting in wells, does not disturb reservoir fluid flows (because seismic waves usually cause very small strains in reservoir rocks), and does not cause precipitation of chemicals in the reservoir.The effectiveness of seismic methods in monitoring EOR processes depends on the velocity and amplitude changes of the seismic waves caused by these processes. Intuitively, the injected CO 2 will increase the compressibility and change the density (either increase or decrease, depending on the pore pressure) of reservoir rocks. These changes will in turn affect the propagation characteristics of the seismic waves. The quantitative effects of CO 2 flooding on wave characters are not well known, however, and no laboratory or field experiments on such effects have thus far been published. Before applying seismic methods in the field, it is therefore necessary to investigate the effects of CO 2 flooding on the seismic properties of reservoir rocks saturated with hydrocarbons in the laboratory .Both compressional-and shear-wave velocities in seven sandstones of various porosities and compressiona...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Effects of CO2 Flooding on Wave Velocities in Rocks With Hydrocarbons

Wang¹,

Nur²

1989

SPE Reservoir Engineering

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“…The laboratory measurement on heavy oil saturated core samples showed large decreases in seismic rock velocity when the viscous oil was heated (Nur et al, 1984;Wang and Nur, 1988;Nur, 1989). These rock physics observations have now been validated by many 4-D seismic field data with steam injection projects (Pullin et al, 1987;Eastwood et al, 1994;Jenkins et al, 1997).…”

Section: Introductionmentioning

confidence: 69%

Streamline-Based Time Lapse Seismic Data Integration Incorporating Pressure and Saturation Effects

Watanabe

Han

Datta‐Gupta

et al. 2013

Day 2 Tue, October 01, 2013

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We present an efficient history matching approach that simultaneously integrates 4-D repeat seismic surveys with well production data. This approach is particularly well-suited for the calibration of the reservoir properties of high-resolution geologic models because the seismic data is areally dense but sparse in time, while the production data is continuous in time but averaged over interwell spacing. The joint history matching is performed using streamline-based sensitivities derived from either finite-difference or streamline-based flow simulation. Previous approaches to seismic data integration have mostly incorporated saturation effects but the pressure effects have largely been ignored. We propose, for the first time, streamline-based analytic approaches to compute parameter sensitivities that relate the seismic data to reservoir properties while accounting for both pressure and saturation effects via appropriate rock physics models. The inverted seismic data (e.g., changes in acoustic impedance or fluid saturations), is distributed as a 3-D high-resolution grid cell property or as a vertically integrated two-dimensional map. We derive pressure drop sensitivities along streamlines in addition to our previous work of water saturation sensitivity computation. The novelty of the method lies in the analytic sensitivity computations which make it computationally efficient for high resolution geologic models. We demonstrate the versatility of our approach by implementing it in a finite difference simulator which incorporates detailed physical processes, while the streamline trajectories provide for rapid evaluation of the sensitivities. The efficacy of our proposed approach is demonstrated with both synthetic and field applications. The synthetic example is the SPE benchmark Brugge field case. The field example involves waterflooding of a North Sea reservoir with multiple seismic surveys. For both the synthetic and the field cases, the advantages of incorporating the time-lapse variations are clearly demonstrated through improved estimation of the permeability distribution, pressure profile, and fluid saturation evolution and swept volumes.

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“…Collectively, they demonstrate that core samples filled with heavy crude exhibit a decrease in both the compressional and shear wave acoustic velocity fields as they are heated (Tosaya, Nur, Da Prat, 1984;Wang and Nur, 1986;Nur and Wang, 1987). For example, laboratory experiments on unconsolidated sandstone core samples saturated with heavy crude under a confining pressure of 15 MPa have documented decreases in P-wave velocity of greater than 30 percent as the temperature increases from 70 to 250 degrees Fahrenheit (Wang and Nur, 1986). This study also showed that the shear wave velocity can decrease up to 9 percent in consolidated sandstone samples saturated with heavy crude as the temperature increases from 70 to 250 degrees Fahrenheit at a confining pressure of 15 MPa.…”

Section: Petrophysical Basis For Interpretationmentioning

confidence: 99%

Applications of Cross-Borehole Seismic Tomography To Monitor EOR Displacement Fronts in Heavy-Oil Fields of Kern County, California

Hutt

Justice

Vassiliou

et al. 1989

SPE Annual Technical Conference and Exhibition

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Cross-borehole seismic tomography has been applied to assist in the monitoring of an EOR displacement front in a heavy oil field located in Kern County, California. Results from this survey indicate that tomographically processed cross-borehole seismic surveys can image variations in the velocity field of the subsurface. Several factors including the temperature, type, and physical state of the pore filling material strongly affect the velocity field of a ·reservoir. Crossborehole velocity profiles, referred to as tomograms, are interpreted to provide insight into the physical changes taking place in the reservoir as an EOR process progresses.

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Effect of temperature on wave velocities in sands and sandstones with heavy hydrocarbons

Cited by 20 publications

References 3 publications

Effects of CO2 Flooding on Wave Velocities in Rocks With Hydrocarbons

Effects of CO2 Flooding on Wave Velocities in Rocks With Hydrocarbons

Streamline-Based Time Lapse Seismic Data Integration Incorporating Pressure and Saturation Effects

Applications of Cross-Borehole Seismic Tomography To Monitor EOR Displacement Fronts in Heavy-Oil Fields of Kern County, California

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