Seismic structure and texture analyses for fractured reservoir characterization: An integrated workflow

2017 ◽  
Vol 5 (4) ◽  
pp. T623-T639 ◽  
Author(s):  
Dengliang Gao ◽  
Taizhong Duan
Keyword(s):  
Texture Analysis ◽  
Structure Analysis ◽  
Fractured Reservoirs ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Seismic Structure ◽  
Fractured Reservoir ◽  
Reservoir Prediction ◽  
Gas Field ◽  
Fracture Characteristics

Fractured reservoir prediction is risky and challenging because of the variability in fracture characteristics and the lack of direct observational data in the subsurface. To reduce the risk and challenge, we have developed an integrated workflow to predict fractured reservoirs based on 3D seismic data. The workflow begins with reservoir structure analysis from seismic reflection geometry, which is referred to as seismic structure analysis, to define fracture intensity and fracture orientation using maximum curvature and maximum flexure algorithms. Next, the workflow proceeds with reservoir texture analysis from seismic amplitude signal, which is referred to as seismic texture analysis, to evaluate fracture scale and reservoir facies using waveform regression and calibration algorithms. The results from seismic structure and texture analyses are then used for modeling reservoir properties and fracture networks. Each algorithmic method in the workflow is tested in a siliciclastic tight-sand reservoir in the Teapot Dome oil field (Powder River Basin) and in a carbonate reservoir in the South Pars gas field (Persian Gulf Basin). The test results reveal the previously unknown reservoir heterogeneity and anisotropy that are interpreted to be attributable to the variability in fracture characteristics. It is concluded that the integrated workflow based on seismic structure and texture analyses could potentially contribute to reducing the risk and challenge in characterizing fractured reservoirs in the subsurface.

Analysis of multiazimuthal VSP data for anisotropy and AVO

Geophysics ◽  
1999 ◽  
Vol 64 (4) ◽  
pp. 1172-1180 ◽  
Author(s):  
W. Scott Leaney ◽  
Colin M. Sayers ◽  
Douglas E. Miller
Keyword(s):  
Fractured Reservoirs ◽  
Vertical Axis ◽  
Horizontal Stress ◽  
Azimuthal Anisotropy ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Fractured Reservoir ◽  
Data Set ◽  
Vsp Data ◽  
The Impact

Multioffset vertical seismic profile (VSP) experiments, commonly referred to as walkaways, enable anisotropy to be measured reliably in the field. The results can be fed into modeling programs to study the impact of anisotropy on velocity analysis, migration, and amplitude versus offset (AVO). Properly designed multioffset VSPs can also provide the target AVO response measured under optimum conditions, since the wavelet is recorded just above the reflectors of interest with minimal reflection point dispersal. In this paper, the multioffset VSP technique is extended to include multioffset azimuths, and a multiazimuthal multiple VSP data set acquired over a carbonate reservoir is analyzed for P-wave anisotropy and AVO. Direct arrival times down to the overlying shale and reflection times and amplitudes from the carbonate are analyzed. Data analysis involves a three‐term fit to account for nonhyperbolic moveout, dip, and azimuthal anisotropy. Results indicate that the overlying shale is transversely isotropic with a vertical axis of symmetry (VTI), while the carbonate shows 4–5% azimuthal anisotropy in traveltimes. The fast direction is consistent with the maximum horizontal stress orientation determined from break‐out logs and is also consistent with the strike of major faults. AVO analysis of the reflection from the top of the carbonate layer shows a critical angle reduction in the fast direction and maximum gradient in the slow direction. This agrees with modeling and indicates a greater amplitude sensitivity in the slow direction—the direction perpendicular to fracture strike. In principle, 3-D surveys should have wide azimuthal coverage to characterize fractured reservoirs. If this is not possible, it is important to have azimuthal line coverage in the minimum horizontal stress direction to optimize the use of AVO for fractured reservoir characterization. This direction can be obtained from multiazimuthal walkaways using the azimuthal P-wave analysis techniques presented.

scholarly journals Seismic characterization of fractured reservoirs by focusing Gaussian beams

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. A23-A28 ◽  
Author(s):  
Yingcai Zheng ◽  
Xinding Fang ◽  
Michael C. Fehler ◽  
Daniel R. Burns
Keyword(s):  
Seismic Data ◽  
Fractured Reservoirs ◽  
Oil Production ◽  
Oil Field ◽  
Critical Parameters ◽  
Gaussian Beams ◽  
Fractured Reservoir ◽  
Fracture Orientation ◽  
Double Beam

Naturally fractured reservoirs occur worldwide, and they account for the bulk of global oil production. The most important impact of fractures is their influence on fluid flow. To maximize oil production, the characterization of a fractured reservoir at the scale of an oil field is very important. For fluid transport, the critical parameters are connectivity and transmittivity plus orientation. These can be related to fracture spacing, compliance, and orientation, which are the critical seismic parameters of rock physics models. We discovered a new seismic technique that can invert for the spatially dependent fracture orientation, spacing, and compliance, using surface seismic data. Unlike most seismic methods that rely on using singly scattered/diffracted waves whose signal-to-noise ratios are usually very low, we found that waves multiply scattered by fractures can be energetic. The direction information of the fracture multiply scattered waves contains fracture orientation and spacing information, and the amplitude of these waves gives the compliance. Our algorithm made use of the interference of two true-amplitude Gaussian beams emitted from surface source and receiver arrays that are extrapolated downward and focused on fractured reservoir targets. The double beam interference pattern provides information about the three fracture parameters. We performed a blind test on our methodology. A 3D model with two sets of orthogonal fractures was built, and a 3D staggered finite-difference method using the Schoenberg linear-slip boundary condition for fractures was used to generate the synthetic surface seismic data set. The test results showed that we were able to not only invert for the fracture orientation and spacing, but also the compliance field.

Research and Application of Spectral Decomposition in Carbonate Reservoir and Fault Identification in MaiJie Let Gas Field, Amu Darya Basin

2012 ◽  
Vol 616-618 ◽  
pp. 141-144
Author(s):  
Hao Yu ◽  
Jin Song Li ◽  
Yan Zhang ◽  
Guang Cheng Xu
Keyword(s):  
Spectral Decomposition ◽  
Carbonate Reservoir ◽  
Fault System ◽  
Reservoir Prediction ◽  
Gas Field ◽  
Seismic Section ◽  
Response Characteristics ◽  
Amu Darya ◽  
S Transform ◽  
The Time Domain

Spectral decomposition is to convert seismic signals from the time domain to the frequency domain by mathematical transformation, and analyze amplitude and phase response characteristics of different scale geological bodies. Spectral decomposition could get higher resolution than conventional seismic data. In the identification of the fault system, it is fit for fault interpretation and plane combination of the sections. In the reservoir prediction, it can identify the shape and contour of the reservoir. This document analyzed algorithm and applicability of short time Fourier transform, continuous wavelet transform and S-transform. Using these three methods for carbonate reservoir identification in MaiJie let gas field, Amu Darya Basin, it proves that the frequency division section is more clearly than conventional seismic section in reservoir and fault description. And S-transform gets the best result.

scholarly journals The effect of gravity drainage mechanism on oil recovery by reservoir simulation; a case study in an Iranian highly fractured reservoir

2021 ◽  
Author(s):  
K. Zobeidi ◽  
M. Mohammad-Shafie ◽  
M. Ganjeh-Ghazvini
Keyword(s):  
Oil Recovery ◽  
Reservoir Simulation ◽  
Fractured Reservoirs ◽  
Saturation Pressure ◽  
Oil Field ◽  
Recovery Factor ◽  
Real Field ◽  
Gravity Drainage ◽  
Special Importance ◽  
Fractured Reservoir

AbstractA comprehensive reservoir simulation study was performed on an oil field that had a wide fracture network and could be considered a typical example of highly fractured reservoirs in Iran. This field is located in southwest of Iran in Zagros sedimentary basin among several neighborhood fields with relatively considerable fractured networks. In this reservoir, the pressure drops below the saturation pressure and causes the formation of a secondary gas cap. This can help to better assess the gravity drainage phenomenon. We decided to investigate and track the effect of gravity drainage mechanism on the recovery factor of oil production in this field. In this study, after/before the implementation of gas injection scenarios with different discharges, the contribution of gravity drainage mechanism to the recovery factor was found more than 50%. Considering that a relatively large number of studies have been conducted on this field simultaneously with the growth of information from different aspects and this study is the last and most comprehensive study and also the results are extracted from real field data using existing reservoir simulators, it is of special importance and can be used by researchers.

Gas Cap and Oil Rim Collaborative Development Technique Policy of Carbonate Reservoir with Condensate Gas Cap

2013 ◽  
Vol 734-737 ◽  
pp. 1381-1390
Author(s):  
Heng Song ◽  
Zi Fei Fan ◽  
Lun Zhao ◽  
An Gang Zhang
Keyword(s):  
Large Scale ◽  
Oil And Gas ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Pressure Balance ◽  
Gas Reservoirs ◽  
Gas Field ◽  
Collaborative Development ◽  
Technical Problems ◽  
Oil And Gas Reservoirs

Zhanazhol oilfield is a large-scale complicated carbonated oil and gas field , Гnorth is the main oil and gas reservoirs of the oil field, The gas cap index is 0.38, the gas cap on a high condensate content. Reservoir development for nearly 25 years, exploitation in the past only to oil ring. Due to insufficient water injection in early age, the oil ring pressure dropped substantially, and the formation pressure to maintain the level of only 58%. For oil and gas reservoirs with a condensate gas cap, gas cap and oil ring at the same pressure system, with the decline in the pressure of the oil ring, the gas cap continue to spread to the oil region, while there are a large number of condensate oil anti-condensate from the gas cap, which loss into the formation. In this paper, the authors consider the characteristics of the oil and gas reservoirs and research the technique policy of collaborative development, These are all in order to solve technical problems, which is keep the pressure balance between the gas cap and oil ring during collaborative development. Not only provide technical to support the rational and efficient development of the Г North oil and gas reservoirs, but also provide a stable source for natural gas pipeline from Kazakhstan to China.

scholarly journals Injection-production optimization of carbonate reservoir based on an inter-well connectivity model

2021 ◽  
pp. 014459872199465
Author(s):  
Yuhui Zhou ◽  
Sheng Lei ◽  
Xuebiao Du ◽  
Shichang Ju ◽  
Wei Li
Keyword(s):  
History Matching ◽  
Water Injection ◽  
Field Application ◽  
Carbonate Reservoir ◽  
Production Optimization ◽  
Oil Field ◽  
Carbonate Reservoirs ◽  
Utilization Rate ◽  
Production Volume ◽  
Connectivity Model

Carbonate reservoirs are highly heterogeneous. During waterflooding stage, the channeling phenomenon of displacing fluid in high-permeability layers easily leads to early water breakthrough and high water-cut with low recovery rate. To quantitatively characterize the inter-well connectivity parameters (including conductivity and connected volume), we developed an inter-well connectivity model based on the principle of inter-well connectivity and the geological data and development performance of carbonate reservoirs. Thus, the planar water injection allocation factors and water injection utilization rate of different layers can be obtained. In addition, when the proposed model is integrated with automatic history matching method and production optimization algorithm, the real-time oil and water production can be optimized and predicted. Field application demonstrates that adjusting injection parameters based on the model outputs results in a 1.5% increase in annual oil production, which offers significant guidance for the efficient development of similar oil reservoirs. In this study, the connectivity method was applied to multi-layer real reservoirs for the first time, and the injection and production volume of injection-production wells were repeatedly updated based on multiple iterations of water injection efficiency. The correctness of the method was verified by conceptual calculations and then applied to real reservoirs. So that the oil field can increase production in a short time, and has good application value.

3D Seismic attribute optimization technology and application for dissolution caved carbonate reservoir prediction

2011 ◽  
Author(s):  
Lifeng Liu ◽  
Sam Zandong Sun ◽  
Haiyang Wang ◽  
Haijun Yang ◽  
Jianfa Han ◽  
...  
Keyword(s):  
Carbonate Reservoir ◽  
3D Seismic ◽  
Reservoir Prediction ◽  
Seismic Attribute

Forecasting the Water Flooding for the Production Wells of a Gas Condensate Field with a Fractured Reservoir Type

2021 ◽  
Author(s):  
Pavel Dmitrievich Gladkov ◽  
Anastasiia Vladimirovna Zheltikova
Keyword(s):  
Produced Water ◽  
Fractured Reservoirs ◽  
Gas Condensate ◽  
Water Flooding ◽  
Fractured Reservoir ◽  
Well Performance ◽  
Integrated Monitoring ◽  
Field Development ◽  
Water Gas ◽  
Gas Ratio

Abstract As is known, fractured reservoirs compared to conventional reservoirs have such features as complex pore volume structure, high heterogeneity of the porosity and permeability properties etc. Apart from this, the productivity of a specific well is defined above all by the number of natural fractures penetrated by the wellbore and their properties. Development of fractured reservoirs is associated with a number of issues, one of which is related to uneven and accelerated water flooding due to water breakthrough through fractures to the wellbores, for this reason it becomes difficult to forecast the well performance. Under conditions of lack of information on the reservoir structure and aquifer activity, the 3D digital models of the field generated using the hydrodynamic simulators may feature insufficient predictive capability. However, forecasting of breakthroughs is important in terms of generating reliable HC and water production profiles and decision-making on reservoir management and field facilities for produced water treatment. Identification of possible sources of water flooding and planning of individual parameters of production well operation for the purpose of extending the water-free operation period play significant role in the development of these reservoirs. The purpose of this study is to describe the results of the hydrochemical monitoring to forecast the water flooding of the wells that penetrated a fractured reservoir on the example of a gas condensate field in Bolivia. The study contains data on the field development status and associated difficulties and uncertainties. The initial data were results of monthly analyses of the produced water and the water-gas ratio dynamics that were analyzed and compared to the data on the analogue fields. The data analysis demonstrated that first signs of water flooding for the wells of the field under study may be diagnosed through the monitoring of the produced water mineralization - the water-gas ratio (WGR) increase is preceded by the mineralization increase that may be observed approximately a month earlier. However, the data on the analogue fields shows that this period may be longer – from few months to two years. Thus, the hydrochemical method within integrated monitoring of development of a field with a fractured reservoir could be one of the efficient methods to timely adjust the well operation parameters and may extend the water-free period of its operation.

Seismic attribute for characterization and prediction of carbonate faulted karst reservoirs in Tarim Basin, China

2021 ◽  
pp. 1-36
Author(s):  
Zhiwei Xiao ◽  
Li Wang ◽  
Ruizhao Yang ◽  
Dewei Li ◽  
Lingbin Meng
Keyword(s):  
Tarim Basin ◽  
Oil And Gas ◽  
Prediction Method ◽  
Strike Slip ◽  
Fault System ◽  
Bright Spot ◽  
Upper Ordovician ◽  
Reservoir Prediction ◽  
Seismic Attribute ◽  
Gas Field

An ultradeep, faulted karst reservoir of Ordovician carbonate was discovered in the Shunbei area of the Tarim Basin. Fractured-cavity reservoirs buried beneath the large thickness of upper Ordovician mudstone were formed along the fault-karst belts. The hydrocarbon accumulation in these reservoirs is controlled by the fault system, and the oil-gas accumulation was affected by karstification and hydrothermal reformation. Previous studies and 2D modeling revealed that the reservoirs had “bright spot” amplitude responses like “string beads,” and they have developed along the strike-slip faults. However, describing such a complex fault-controlled karst system is still a difficult problem that has not been well addressed. We have sought to instruct the attribute expression of faulted karst reservoirs in the northern part of the Tarim Basin. We applied coherence and fault likelihood (FL) seismic attributes to image faults and fractures zones. We then used a trend analysis method to calculate the residual impedance from the impedance of the acoustic inversion, using the fact that residual impedance has higher lateral resolution in reservoir predictions. Finally, we integrated the coherence, FL, and residual impedance attributes into a new seismic attribute, the “fault-vuggy body,” with a certain fusion coefficient. The fault-vuggy body attribute establishes a connection between faults and karst cavities. This method could help in the characterization and prediction of carbonate faulted karst reservoirs. Available drilling data were used to validate that the fused fault-vuggy body attribute was an effective reservoir prediction method. As the seismic sections and slices along the layer help delineate, the distribution of bright spots and strike-slip faults indicates that the main strike-slip fault zones are the most favorable reservoirs in the Shunbei Oil and Gas Field.

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