Numerical modeling of seismic responses from fractured reservoirs in 4D monitoring. Part one: seismic responses from fractured reservoirs in carbonate and shale formations

Geophysics ◽  
2021 ◽  
pp. 1-93
Author(s):  
Vladimir Leviant ◽  
Naum Marmalevsky ◽  
Igor Kvasov ◽  
Polina Stognii ◽  
Igor Petrov
Keyword(s):  
Numerical Modeling ◽  
Oil And Gas ◽  
Fractured Reservoirs ◽  
Main Tool ◽  
Time Lapse ◽  
Single Fracture ◽  
Fractured Reservoir ◽  
Seismic Responses ◽  
Shale Formations ◽  
Fracture Opening

One of the most urgent problems of oil and gas reservoir monitoring is the assessment of fractured reservoir infill type – with fluid-filled, gas-filled or closed (no-reservoir situation) fractures, which is of significant value for time-lapse seismic technology. We used the grid-characteristic method (GCM) for numerical modeling of seismic responses from fractured periodic elasto-acoustic structures. We consider every single fracture individually (without using the effective medium approach), and set explicit boundary conditions on fracture surfaces. We assume realistic height-to-thickness ratios – fracture opening (aperture) – equaling 3 to 5 orders of magnitude. These techniques make our models as close to real fractured reservoirs as possible. Analyzing the simulated seismic responses, we solve the problem of assessing fractured reservoir infill type. As a result, previously unknown properties of seismic responses from fractured reservoirs were revealed. We use AVO as the main tool for the analysis of fracture infill type effect on the seismic response in three frequency ranges. Three out of four models exhibit a stable positive AVO gradient regardless of the rock type and frequency range. The analysis of linearized Zoeppritz equations confirms such AVO behavior. We proposed quantitative criteria (indicators) for recognition of a fracture infill type. Amplitude-frequency analysis is shown to expand the capabilities of infill type recognition. Thus, a method for determining fractured reservoir infill type is established for carbonate and shale formations, which could become the basis for a new direction in time-lapse technology.

A Simplified and Efficient Method for Water Flooding Production Index Calculations in Low Permeable Fractured Reservoir

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Shun Liu ◽  
Liming Zhang ◽  
Kai Zhang ◽  
Jianren Zhou ◽  
Heng He ◽  
...  
Keyword(s):  
Fractured Reservoirs ◽  
Water Injection ◽  
Cross Flow ◽  
Production Performance ◽  
Water Flooding ◽  
Simplified Model ◽  
Single Fracture ◽  
Fractured Reservoir ◽  
Production Index ◽  
Future Production

Presently, predicting the production performance of fractured reservoirs is often challenging because of the following two factors: one factor such as complicatedly connected and random distribution nature of the fractures and the other factor includes the limitations of the understanding of reservoir geology, deficient fracture-related research, and defective simulators. To overcome the difficulties of simulating and predicting fractured reservoir under complex circumstances of cross flow, a simplified model, which assumes cross flow only exists in the oil phase segment, is constructed. In the model, the pressure distribution of a single fracture can be described by solving an analytical mathematical model. In addition, due to research and field experience which indicate that cross flow also exists in the mixed-phase segment after water injection, the simplified model is modified to consider cross flow in the whole phase. The model constructed here is applicable for fractured reservoirs especially for a low-permeability fracture reservoir, and it moderately predicts future production index. By using iterative methods, the solution to the model can be feasibly obtained and related production performance index formulas can be derived explicitly. A case study was performed to test the model, and the results prove that it is good.

Seismic Soundoff

2020 ◽  
Vol 39 (1) ◽  
pp. 72-72
Author(s):  
Andrew Geary
Keyword(s):  
Numerical Modeling ◽  
Fractured Reservoirs ◽  
Characteristic Method ◽  
Seismic Responses

The following is an excerpt from SEG's Seismic Soundoff podcast. In this episode, Igor Kvasov, engineering manager at Google and cofounder of SeismoTrack, joins host Andrew Geary to discuss his new book, Numerical Modeling of Seismic Responses from Fractured Reservoirs by the Grid-characteristic Method. This episode is sponsored by TGS. Listen to the full episode at https://seg.org/podcast/post/8688 .

scholarly journals Physical and numerical modeling of tuning and diffraction in azimuthally anisotropic media

Geophysics ◽  
2000 ◽  
Vol 65 (5) ◽  
pp. 1613-1621 ◽  
Author(s):  
Richard L. Gibson ◽  
Stephen Theophanis ◽  
M. Nafi Toksöz
Keyword(s):  
Numerical Modeling ◽  
Fractured Reservoirs ◽  
Homogeneous Model ◽  
Azimuthal Anisotropy ◽  
P Wave ◽  
Orthorhombic Symmetry ◽  
Fractured Reservoir ◽  
Sh Wave ◽  
Wave Data ◽  
Ray Methods

Fractured reservoirs are an important target for exploration and production geophysics, and the azimuthal anisotropy often associated with these reservoirs can strongly influence seismic wave propagation. We created a physical model of a fractured reservoir to simulate some of these propagation effects. The reservoir is represented by a phenolite disk that is thin with respect to the elastic wavelengths in the experiment, creating model dimensions that are representative of realistic reservoirs. Phenolite is strongly anisotropic with orthorhombic symmetry, which suggests that azimuthal amplitude versus offset (AVO) effects should be obvious in data. We acquired both SH- and P-wave data in common‐offset gathers with a near offset and a far offset and found that although the SH-wave data show clear azimuthal variations in AVO, the P-wave signals show no apparent changes with azimuth. We then applied numerical modeling to analyze the data. Because ray methods cannot model diffractions from the disk edge, we first used a ray‐Born technique to simulate variations in waveforms associated with such scattering. The synthetic seismograms reproduced variations in the SH-wave waveforms accurately, though the amplitude contrast between acquisition azimuths was overestimated. Assuming a laterally homogeneous model, we then applied ray methods to simulate tuning effects in SH- and P-wave data and confirmed that in spite of the large contrasts in elastic properties, the tuning of the P-wave reflections from the thin disk changed so there was negligible contrast in AVO with azimuth. Models of field scale reservoirs showed that the same effects could be expected for field applications.

Reviews

2021 ◽  
Vol 40 (2) ◽  
pp. 154-154
Author(s):  
Edward S. Krebes
Keyword(s):  
Numerical Modeling ◽  
Fractured Reservoirs ◽  
Characteristic Method ◽  
Seismic Responses

Numerical Modeling of Seismic Responses from Fractured Reservoirs by the Grid-characteristic Method, by Vladimir Leviant, Igor Kvasov, and Igor Petrov, ISBN 978-1-560-80366-9, SEG, 272 p.

scholarly journals Innovative solutions in construction of deep industrial brine, oil and gas wells in deformable fractured reservoirs

2021 ◽  
Vol 44 (2) ◽  
pp. 125-133
Author(s):  
A. G. Vakhromeev ◽  
S. A. Sverkunov ◽  
R. Kh. Akchurin ◽  
V. M. Ivanishin ◽  
V. V. Ruzhich ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Fractured Reservoirs ◽  
Fluid Pressure ◽  
Natural State ◽  
Main Task ◽  
Fractured Reservoir ◽  
Drilling Mud ◽  
Innovative Solutions ◽  
Formation Zone ◽  
Technical Solutions

The paper deals with the methodological features of drilling and completion of wells in the fractured natural reservoirs containing oil and gas accumulations with different reservoir pressures of fluid-pressure systems from abnormally high to abnormally low. The authors had studied the fluid-pressure systems of industrial lithium-bromine brines, oil and gas fields and accumulations in the south of the Siberian platform for the period from 1983 to 2019. The article summarizes the main results, including new technical solutions protected by the Russian Federation patents. The authors proposed and patented a series of new technical solutions for the immediate consolidation of natural permeable fractures during the primary opening of the reservoir by drilling, as applied to a fractured reservoir. The main task of the study is to preserve the permeability of the fractured system in the bottomhole formation zone under the action of compressive stresses (rock mass) that increase with the formation of a drawdown cone, primarily in the bottomhole formation zone with the increase in the drawdown (ΔP) above critical values. Such an area is the bottomhole formation zone within a radius of the first meters around the well that penetrated the fractured reservoir. Practice has proved that the use of innovative solutions through the advanced consolidation of permeable fractures in the bottomhole formation zone (of fluid-producing oil- and gas-bearing, water-bearing reservoir) in the open (initial natural) state ensures the preservation of natural permeability of natural filtering fractures of the reservoir with the fluid system reservoir pressure from anomalously low to abnormally high. The solution ensures constant permeability of the fractured filtration system throughout the cleaning cycles of the bottomhole formation zone rocks from drilling mud, obtaining of the true calculated hydrodynamic parameters based on the results of well testing in the modes of the “steady-state production method” and well flow rate (productivity) stabilization under further well operation.

Scale discrepancy paradox between observation and modelling in fractured reservoir models in oil and gas industry.

2020 ◽  
Author(s):  
Pascal Richard ◽  
Loïc Bazalgette
Keyword(s):  
Oil And Gas ◽  
Dynamic Models ◽  
Fractured Reservoirs ◽  
Research Work ◽  
Oil And Gas Industry ◽  
Naturally Fractured Reservoirs ◽  
Natural Fracture ◽  
Fractured Reservoir ◽  
Dynamic Data ◽  
Gas Industry

<p>Naturally fractured reservoirs represent one of the most challenging resource in the oil and gas industry. The understanding based on centimeter scale observations is upscaled and modeled at 100-meter scale.</p><p>In this paper, we will illustrate with case study examples of conceptual fracture model elaborated using static and dynamic data, the disconnect between the scale of observation and the scale of modelling. We will also discuss the potential disconnect between the detail of fundamental, but necessary, research work in universities against the coarse resolution of the models built in the oil industry, and how we can benefit of the differences in scales and approaches.</p><p> </p><p>The appraisal and development of fractured reservoirs offer challenges due to the variations in reservoir quality and natural fracture distribution. Typically, the presence of open, connected fractures is one of the key elements to achieve a successful development. Fracture modelling studies are carried out routinely to support both appraisal and development strategies of these fractured reservoirs.</p><p>Overall fracture modelling workflow consists first of a fracture characterization phase concentrating on the understanding of the deformation history and the evaluation of the nature, type and distribution of the fractures; secondly of a fracture modelling part where fracture properties for the dynamic simulation are generated and calibrated against dynamic data. The pillar of the studies is the creation of 3D conceptual fracture diagrams/concepts which summarize both the understanding and the uncertainty of the fracture network of interest. These conceptual diagrams rely on detailed observations at the scale of the wellbore using core and borehole image data which are on contrasting scale compare to the 10’s of meters to 100’s of meter scale of the grid cells of the dynamic models used for the production history match and forecast. These contrasting scales will be the thread of the presentation.</p>

FRACTAL ANALYSIS OF FRACTURE INCREASING SPONTANEOUS IMBIBITION IN POROUS MEDIA WITH GAS-SATURATED

2013 ◽  
Vol 24 (08) ◽  
pp. 1350056 ◽  
Author(s):  
JIANCHAO CAI ◽  
SHUYU SUN
Keyword(s):  
Fractal Analysis ◽  
Fractured Reservoirs ◽  
Spontaneous Imbibition ◽  
Gravity Force ◽  
Single Fracture ◽  
Liquid Density ◽  
Fractured Reservoir ◽  
Single Plane ◽  
Matrix Blocks ◽  
Wetting Liquid

Spontaneous imbibition (SI) of wetting liquid into matrix blocks due to capillary pressure is regarded as an important recovery mechanism in low permeability fractured reservoir. In this paper, an analytical model is proposed for characterizing SI horizontally from a single plane fracture into gas-saturated matrix blocks. The presented model is based on the fractal character of pores in porous matrix, with gravity force included in the entire imbibition process. The accumulated mass of wetting liquid imbibed into matrix blocks is related to a number of factors such as contact area, pore fractal dimension, tortuosity, maximum pore size, porosity, liquid density and viscosity, surface tension, contact angle, as well as height and tilt angle of the fracture. The mechanism of fracture-enhanced SI is analyzed accordingly. Because of the effect of fracture, the gravity force is positive to imbibition process. Additionally, the farther away from the fracture top of the pore, the more influential the hydrostatic pressure is upon the imbibition action. The presented fractal analysis of horizontal spontaneous imbibition from a single fracture could also shed light on the scaling study of the mass transfer function between matrix and fracture system of fractured reservoirs.

Scale discrepancy paradox between observation and modelling in fractured reservoir models in oil and gas industry.

2021 ◽  
Author(s):  
Pascal Richard ◽  
Loic Bazalgette
Keyword(s):  
Oil And Gas ◽  
Dynamic Models ◽  
Fractured Reservoirs ◽  
Research Work ◽  
Oil And Gas Industry ◽  
Naturally Fractured Reservoirs ◽  
Natural Fracture ◽  
Fractured Reservoir ◽  
Dynamic Data ◽  
Gas Industry

<p>Naturally fractured reservoirs represent one of the most challenging resource in the oil and gas industry. The understanding based on centimeter scale observations is upscaled and modeled at 100-meter scale.</p><p>In this paper, we will illustrate with case study examples of conceptual fracture model elaborated using static and dynamic data, the disconnect between the scale of observation and the scale of modelling. We will also discuss the potential disconnect between the detail of fundamental, but necessary, research work in universities against the coarse resolution of the models built in the oil industry, and how we can benefit of the differences in scales and approaches.</p><p> </p><p>The appraisal and development of fractured reservoirs offer challenges due to the variations in reservoir quality and natural fracture distribution. Typically, the presence of open, connected fractures is one of the key elements to achieve a successful development. Fracture modelling studies are carried out routinely to support both appraisal and development strategies of these fractured reservoirs.</p><p>Overall fracture modelling workflow consists first of a fracture characterization phase concentrating on the understanding of the deformation history and the evaluation of the nature, type and distribution of the fractures; secondly of a fracture modelling part where fracture properties for the dynamic simulation are generated and calibrated against dynamic data. The pillar of the studies is the creation of 3D conceptual fracture diagrams/concepts which summarize both the understanding and the uncertainty of the fracture network of interest. These conceptual diagrams rely on detailed observations at the scale of the wellbore using core and borehole image data which are on contrasting scale compare to the 10’s of meters to 100’s of meter scale of the grid cells of the dynamic models used for the production history match and forecast. These contrasting scales will be the thread of the presentation.</p>

scholarly journals Joint flow seismic inversion for characterizing fractured reservoirs: Theoretical approach and numerical modeling

2013 ◽  
Author(s):  
Peter K. Kang ◽  
Yingcai Zheng ◽  
Xinding Fang ◽  
Rafal Wojcik ◽  
Dennis McLaughlin ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Theoretical Approach ◽  
Fractured Reservoirs ◽  
Seismic Inversion
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