Predicting acoustic-wave velocities and fluid sensitivity to elastic properties in fractured carbonate formation

2017 ◽  
Vol 5 (1) ◽  
pp. SB69-SB80 ◽  
Author(s):  
Jingjing Xu ◽  
Maojin Tan ◽  
Xiaochang Wang ◽  
Chunping Wu
Keyword(s):  
Elastic Properties ◽  
Carbonate Rocks ◽  
Seismic Inversion ◽  
Carbonate Reservoir ◽  
S Wave ◽  
Mineral Concentration ◽  
Fracture Porosity ◽  
Wave Velocities ◽  
Carbonate Formation ◽  
Fractured Carbonate

Estimation of S-wave velocity is one of the most critical steps for prestack seismic inversion. Based on the petrophysical model of fractured carbonate rocks, theoretical methods are firstly investigated for estimating P- and S-wave velocities in the presence of fractures. Then, the methods of calculating elastic properties in fractured carbonate rocks are discussed. The mineral concentration, total porosity, and fracture porosity from core X-ray diffraction and routine core measurements or log interpretation results are used to estimate the P- and S-wave velocities. In the given carbonate rock model, the elastic properties of carbonate rocks with different porosity and fractures are calculated. Two field tests prove that the proposed new method is effective and accurate. Furthermore, the model is useful for fluid identification, which is one of the most outstanding problems for carbonate reservoir description. The simulation results suggest that the larger the fracture porosity is, the easier fluid typing. In Tahe Oilfield, the elastic properties of different fluid zones indicate that bulk modulus and Young’s modulus are more sensitive to fluid than shear modulus, the Lamé constant, and Poisson’s ratio.

Predicting subsurface CO2 movement: From laboratory to field scale

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. M27-M37 ◽  
Author(s):  
Ranjana Ghosh ◽  
Mrinal K. Sen
Keyword(s):  
Elastic Properties ◽  
Carbonate Rocks ◽  
Water Saturation ◽  
Time Lapse ◽  
Carbonate Reservoir ◽  
S Wave ◽  
Permeability Enhancement ◽  
Proposed Model ◽  
Porosity And Permeability ◽  
Frequency Dependent Model

Finding an appropriate model for time-lapse seismic monitoring of [Formula: see text]-sequestered carbonate reservoir poses a great challenge because carbonate-rocks have varying textures and highly reactive rock-fluid system. We introduced a frequency-dependent model based on Eshelby’s inclusion and differential effective medium (DEM) theory that can account for heterogeneity in microstructure of rocks and squirt flow. We showed that the estimated velocities from the modified DEM theory match well with the laboratory measurements (ultrasonic) of velocities of carbonate rocks saturated with [Formula: see text]-rich water. The theory predicts significant decrease in saturated P- and S-wave velocities in the seismic frequency band as a consequence of porosity and permeability enhancement by the process of chemical dissolution of carbonates with the saturating fluid. The study also showed the combined effect of chemical reaction and free [Formula: see text] saturation on the elastic properties of rock. We observed that the velocity dispersion and attenuation increased from complete gas saturation to water saturation. The proposed model can be used to invert geophysical measurements to detect changes in elastic properties of a carbonate reservoir and interpret the extent of [Formula: see text] movement with time. These are the key elements to ensure that sequestration will not damage underground geologic formation and [Formula: see text] storage is secure and environmentally acceptable.

scholarly journals Elastic properties of continental carbonates: From controlling factors to an applicable model for acoustic-velocity predictions

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. MR45-MR59 ◽  
Author(s):  
Jean-Baptiste Regnet ◽  
Jérôme Fortin ◽  
Aurélien Nicolas ◽  
Matthieu Pellerin ◽  
Yves Guéguen
Keyword(s):  
Aspect Ratio ◽  
Elastic Properties ◽  
Carbonate Rocks ◽  
Effective Medium ◽  
Acoustic Velocity ◽  
Controlling Factors ◽  
S Wave ◽  
Wave Velocities ◽  
Diagenetic Alteration ◽  
Continental Carbonates

We have provided new insights into the controlling factors of elastic properties in continental carbonate rocks and introduced an applicable model for acoustic-velocity predictions in such a medium. Petrophysical properties (porosity, permeability, P- and S-wave velocities) from laboratory measurements have been coupled with thin-section observations and characterizations, and X-ray diffraction (XRD) analyses. A major achievement is the establishment of the link between the mineralogical composition and the P- and S-wave velocity dispersion at a given porosity. This reflects the subtle interplay between physicochemical and biological precipitation of continental carbonates, which can also be associated with a strong influence of detrital mineralogical inputs. The result is a mineralogical commixture, coupled to a wide array of pore types inherited from the strong ability of carbonate rocks to undergo diagenetic alteration. The proposed model takes into account the elastic moduli of the minerals, porosity, and pore shape, and it is based on the effective medium theory. We have considered the case in which the medium contained randomly oriented pores with different aspect ratios. Overall, the fit between the predicted trends and the experimental data is fairly good, especially for calcite and quartz matrix mineralogy. The results are even better when considering mineralogy inferred from XRD data, although in some case, and despite the aspect ratio variation in both simulations, the model fails to accurately predict the P-wave velocities. This probably means that another factor is at stake beside mineralogy. This can be explained by the limitation of the effective medium approach, which oversimplifies the reality and fails to account for the variability of some aspect ratio from one inclusion to another.

scholarly journals Prediction of Dynamic Elastic Properties for Mishrif formation in West Qurna-1 oil field: an experimental work

2021 ◽  
Author(s):  
ahmed wattan ◽  
Mohammed AL‑Jawad
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Carbonate Rocks ◽  
Young's Modulus ◽  
Compressional Wave ◽  
Oil Field ◽  
S Wave ◽  
Wave Velocities ◽  
The Relationship ◽  
Elastic Characteristics

Abstract Shear and compressional wave velocities are useful for drilling operations, the exploration of reservoirs, stimulation processes, and hydraulic fracturing. An ultrasonic device will be used in this investigation to anticipate and analyze the elastic characteristics of carbonate rocks. At the summit of the field, the well WQ1-20 obtained samples of the Mishrif formation from a variety of various depths. The number of samples taken from the well is nine from different units whereas the number of samples taken from the main unit (MB2) was five. The relations between the elastic properties for the carbonate rocks with P-and S-waves were defined. The relations between Vp and Vs with elastic properties were defined by applied Regression analysis. The results showed that a linear relationship between P-and S-wave velocities with the elastic properties of the carbonate rocks. It is found that the relationship between Vp and Young's modulus (E) is R2 equal to 0.979 while the relationship between Vs and Young's modulus (E) is R2 equal to 0.925. The relationship between shear modulus and Vs is good in comparison with Vp where the values of R2 were 0.985 and 0.94 respectively. R2 values for the Bulk modulus and Lame's constant of Vp are 0.925 and 0.6, respectively, while the values for Vs are 0.925 and 0.6 for the latter. The relation between Vp/Vs ratio with Poisson’s ratio showed a good R2 with a value of 0.97. When it comes to predicting the dynamic elastic characteristics of a material, the ultrasonic approach may be regarded as a cost-effective, easy, and non-destructive method.

Petrophysical properties variation of bitumen-bearing carbonates at increasing temperatures from laboratory to model

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. MR297-MR308
Author(s):  
Roberta Ruggieri ◽  
Fabio Trippetta
Keyword(s):  
Central Italy ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Petrophysical Properties ◽  
S Wave ◽  
Reservoir Properties ◽  
Velocity Change ◽  
Seismic Properties ◽  
Wave Velocities ◽  
Velocity Changes

Variations in reservoir seismic properties can be correlated to changes in saturated-fluid properties. Thus, the determination of variation in petrophysical properties of carbonate-bearing rocks is of interest to the oil exploration industry because unconventional oils, such as bitumen (HHC), are emerging as an alternative hydrocarbon reserve. We have investigated the temperature effects on laboratory seismic wave velocities of HHC-bearing carbonate rocks belonging to the Bolognano Formation (Majella Mountain, central Italy), which can be defined as a natural laboratory to study carbonate reservoir properties. We conduct an initial characterization in terms of porosity and density for the carbonate-bearing samples and then density and viscosity measurements for the residual HHC, extracted by HCl dissolution of the hosting rock. Acoustic wave velocities are recorded from ambient temperature to 90°C. Our acoustic velocity data point out an inverse relationship with temperature, and compressional (P) and shear (S) wave velocities show a distinct trend with increasing temperature depending on the amount of HHC content. Indeed, samples with the highest HHC content show a larger gradient of velocity changes in the temperature range of approximately 50°C–60°C, suggesting that the bitumen can be in a fluid state. Conversely, below approximately 50°C, the velocity gradient is lower because, at this temperature, bitumen can change its phase in a solid state. We also propose a theoretical model to predict the P-wave velocity change at different initial porosities for HHC-saturated samples suggesting that the velocity change mainly is related to the absolute volume of HHC.

Improving Porosity–Velocity Relationships Using Carbonate Pore Types

2015 ◽  
Vol 23 (04) ◽  
pp. 1540006 ◽  
Author(s):  
Tingting Zhang ◽  
Yuefeng Sun ◽  
Qifeng Dou ◽  
Hanrong Zhang ◽  
Tonglou Guo ◽  
...  
Keyword(s):  
Pore Structure ◽  
Acoustic Impedance ◽  
Carbonate Rocks ◽  
Seismic Inversion ◽  
Carbonate Reservoir ◽  
Reservoir Rocks ◽  
Fluid Content ◽  
Fracture Fluid ◽  
Poroelastic Model ◽  
Pore Types

Acoustic impedance in carbonates is influenced by factors such as porosity, pore structure/fracture, fluid content, and lithology. Occurrence of moldic and vuggy pores, fractures and other pore structures due to diagenesis in carbonate rocks can greatly complicate the relationships between impedance and porosity. Using a frame flexibility factor ([Formula: see text]) derived from a poroelastic model to characterize pore structure in reservoir rocks, we find that its product with porosity can result in a much better correlation with sonic velocity ([Formula: see text] = [Formula: see text]) and acoustic impedance ([Formula: see text] = [Formula: see text], where A, B, C and D is 6.60, 0.03, 18.3 and 0.09, respectively for the deep low-porosity carbonate reservoir studied in this paper. These new relationships can also be useful in improving seismic inversion of ultra-deep hydrocarbon reservoirs in other similar environments.

scholarly journals Optimization of Rock Physics Models by Combining the Differential Effective Medium (DEM) and Adaptive Batzle-Wang Methods in “R” Field, East Java

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
M. Wahdanadi Haidar ◽  
Reza Wardhana ◽  
M. Iskan ◽  
M. Syamsu Rosid
Keyword(s):  
Elastic Modulus ◽  
Wave Velocity ◽  
Carbonate Rocks ◽  
Effective Medium ◽  
Carbonate Reservoir ◽  
P Wave ◽  
S Wave ◽  
P Wave Velocity ◽  
Reservoir Conditions ◽  
Pore Types

The pore systems in carbonate reservoirs are more complex than the pore systems in clastic rocks. There are three types of pores in carbonate rocks: interparticle pores, stiff pores and cracks. The complexity of the pore types can lead to changes in the P-wave velocity by up to 40%, and carbonate reservoir characterization becomes difficult when the S-wave velocity is estimated using the dominant interparticle pore type only. In addition, the geometry of the pores affects the permeability of the reservoir. Therefore, when modelling the elastic modulus of the rock it is important to take into account the complexity of the pore types in carbonate rocks. The Differential Effective Medium (DEM) is a method for modelling the elastic modulus of the rock that takes into account the heterogeneity in the types of pores in carbonate rocks by adding pore-type inclusions little by little into the host material until the required proportion of the material is reached. In addition, the model is optimized by calculating the bulk modulus of the fluid filler porous rock under reservoir conditions using the Adaptive Batzle-Wang method. Once a fluid model has been constructed under reservoir conditions, the model is entered as input for the P-wave velocity model, which is then used to estimate the velocity of the S-wave and the proportion of primary and secondary pore types in the rock. Changes in the characteristics of the P-wave which are sensitive to the presence of fluid lead to improvements in the accuracy of the P-wave model, so the estimated S-wave velocity and the calculated ratio of primary and secondary pores in the reservoir are more reliable.

Study on the Construction and Performance of Completion Fluid System in Fractured Carbonate Reservoir

2020 ◽  
Vol 861 ◽  
pp. 388-394
Author(s):  
Cong Bing Chang ◽  
Man Shu ◽  
Yin Fu Han ◽  
Yi Hang Zhang ◽  
Jin Tian ◽  
...  
Keyword(s):  
Early Stage ◽  
Drilling Fluid ◽  
Research Work ◽  
Influence Factors ◽  
Carbonate Reservoir ◽  
Salt Crystallization ◽  
Fluid System ◽  
Carbonate Formation ◽  
Fractured Carbonate ◽  
And Performance

There are microfractures and fractures in the carbonate formation of M oilfield, which are easy to cause collapse and borehole instability. On the basis of the liquefiable cleanflo drilling fluid system for open hole completion of horizontal wells designed in the early stage, this paper has carried out the research work of matching acidizing completion fluid system. In this paper, the influence factors, cleaning ability, compatibility, acidizing situation and protection effect of acidizing completion fluid system are evaluated in laboratory. The way of density adjustment and specific dosage of NaCl and hcoona were established to inhibit the formation of salt crystallization. HTA solid acid and JCI are used to counteract each other to reduce the corrosion of casing steel. The core displacement results show that the permeability recovery value of carbonate core after completion fluid treatment can reach 97.54%, and that of sandstone core after treatment can reach 114.7%. Moreover, the completion fluid system also has a certain acidizing effect, which can not only clean and remove the plugging, but also serve as the early induction of acidizing and stimulation.

scholarly journals The influence of pore system change during CO2 storage on 4D seismic interpretation

2019 ◽  
Vol 74 ◽  
pp. 81
Author(s):  
Lin Li ◽  
Jinfeng Ma
Keyword(s):  
Co2 Storage ◽  
Seismic Inversion ◽  
Pore System ◽  
S Wave ◽  
Wave Velocities ◽  
Rock Testing ◽  
Amplitude Versus Offset ◽  
Weyburn Field ◽  
4D Seismic ◽  
Amplitude Versus

A 4D seismic forward model constitutes the foundation of 4D seismic inversion. Here, in combination with the Gassmann equation, the Digby model is improved to calculate the S-wave velocity, and the resulting equation is verified using rock testing results. Then, considering the influences of changes in the pore pressure, CO2 saturation and porosity on the P- and S- wave velocities, rock testing results from a CO2 injection area in the Weyburn field are used to calculate the P- and S-wave velocities of the reservoir. These P- and S-wave velocities are found to overlap under different pressure conditions with or without considering porosity variations. Therefore, two-layer models and well models are developed to simulate synthetic seismograms; the models considering porosity variations may provide greater seismic responses and different Amplitude Versus Offset (AVO) trends in the synthetic seismogram profiles than those without considering porosity variations. Thus, porosity variations must be considered when establishing 4D seismic forward models.

scholarly journals Measuring ultrasonic characterisation to determine the impact of TOC and the stress field on shale gas anisotropy

2013 ◽  
Vol 53 (1) ◽  
pp. 245 ◽  
Author(s):  
Yazeed Altowairqi ◽  
Reza Rezaee ◽  
Milovan Urosevic ◽  
Claudio Delle Piane
Keyword(s):  
Elastic Properties ◽  
Shale Gas ◽  
Ultrasonic Transducers ◽  
S Wave ◽  
Gas Reservoirs ◽  
Wave Velocities ◽  
Degree Of Anisotropy ◽  
The Impact ◽  
The Relationship ◽  
Dynamic Elastic Properties

While the majority of natural gas is produced from conventional sources, there is significant growth from unconventional sources, including shale-gas reservoirs. To produce gas economically, candidate shale typically requires a range of characteristics, including a relatively high total organic carbon (TOC) content, and it must be gas mature. Mechanical and dynamic elastic properties are also important shale characteristics that are not well understood as there have been a limited number of investigations of well-preserved samples. In this study, the elastic properties of shale samples are determined by measuring wave velocities. An array of ultrasonic transducers are used to measure five independent wave velocities, which are used to calculate the elastic properties of the shale. The results indicated that for the shale examined in this research, P- and S-wave velocities vary depending on the isotropic stress conditions with respect to the fabric and TOC content. It was shown that the isotropic stress significantly impacts velocity. In addition, S-wave anisotropy was significantly affected by increasing stress anisotropy. Stress orientation, with respect to fabric orientation, was found to be an important influence on the degree of anisotropy of the dynamic elastic properties in the shale. Furthermore, the relationship between acoustic impedance (AI) and TOC was established for all the samples.

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