Multiresolution Grid Connectivity-Based Transform for Efficient History Matching of Unconventional Reservoirs

SPE Journal ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 1895-1915 ◽  
Author(s):  
Hyunmin Kim ◽  
Akhil Datta-Gupta
Keyword(s):  
History Matching ◽  
Basis Functions ◽  
Unconventional Reservoirs ◽  
Hydraulic Fractures ◽  
Reservoir Model ◽  
Fracture Properties ◽  
Data Resolution ◽  
Matrix Properties ◽  
The Matrix

Summary Proper characterization of heterogeneous rock properties and hydraulic fracture parameters is essential for optimization of well spacing and reliable estimation of estimated ultimate recovery (EUR) in unconventional reservoirs. High resolution characterization of matrix properties and complex fracture parameters require efficient history matching of well production and pressure response. We propose a novel reservoir model parameterization method to reduce the number of unknowns, regularize the ill-posed problem, and enhance the efficiency of history matching of unconventional reservoirs. The proposed method makes a low-rank approximation of the spatial distribution of reservoir properties taking into account the varying model resolution of the matrix and hydraulic fractures. Typically, hydraulic fractures are represented with much higher resolution through local grid refinements compared to the matrix properties. In our approach, the spatial property distribution of both matrix and fractures is represented using a few parameters via a linear transformation with multiresolution basis functions. The parameters in transform domain are then updated during model calibrations, substantially reducing the number of unknowns. The multiresolution basis functions are constructed by using Eigen-decomposition of an adaptively coarsened grid Laplacian corresponding to the data resolution. Higher property resolution at the area of interest through the adaptive resolution control while keeping the original grid structure improves quality of history matching, reduces simulation runtime, and improves the efficiency of history matching. We demonstrate the power and efficacy of our method using synthetic and field examples. First, we illustrate the effectiveness of the proposed multiresolution parameterization by comparing it with traditional methods. For the field application, an unconventional tight oil reservoir model with a multistage hydraulic fractured well is calibrated using bottomhole pressure and water cut history data. The hydraulic fractures as well as the stimulated reservoir volume (SRV) near the well are represented with higher grid resolution. In addition to matrix and fracture properties, the extent of the SRV and hydraulic fractures are also adjusted through history matching using a multiobjective genetic algorithm. The calibrated ensemble of models are used to obtain bounds of production forecast. Our proposed method is designed to calibrate reservoir and fracture properties with higher resolution in regions that have improved data resolution and higher sensitivity to the well performance data, for example the SRV region and the hydraulic fractures. This leads to a fast and efficient history matching workflow and enables us to make optimal development/completion plans in a reasonable time frame.

Macro- to Atomic-Scale Tailoring of Si3N4 Ceramics to Enhance Properties

2005 ◽  
Vol 287 ◽  
pp. 233-241 ◽  
Author(s):  
Paul F. Becher ◽  
Gayle S. Painter ◽  
Naoya Shibata ◽  
Hua Tay Lin ◽  
Mattison K. Ferber
Keyword(s):  
Electronic Device ◽  
Atomic Level ◽  
Atomic Scale ◽  
Fracture Properties ◽  
Beta Particles ◽  
Preferential Segregation ◽  
Nitride Ceramics ◽  
Theoretical Predictions ◽  
The Matrix

Silicon nitride ceramics are finding uses in numerous engineering applications because of their tendency to form whisker-like microstructures that can overcome the inherent brittle nature of ceramics. Studies now establish the underlying microscopic and atomic-scale principles for engineering a tough, strong ceramic. The theoretical predictions are confirmed by macroscopic observations and atomic level characterization of preferential segregation at the interfaces between the grains and the continuous nanometer thick amorphous intergranular film (IGF). Two interrelated factors must be controlled for this to occur including the generation of the elongated reinforcing grains during sintering and debonding of the interfaces between the reinforcing grains and the matrix. The reinforcing grains can be controlled by (1) seeding with beta particles and (2) the chemistry of the additives, which also can influence the interfacial debonding conditions. In addition to modifying the morphology of the reinforcing grains, it now appears that the combination of preferential segregation and strong bonding of the additives (e.g., the rare earths, RE) to the prism planes can also result in sufficiently weakens the bond of the interface with the IGF to promote debonding. Thus atomic-scale engineering may allow us to gain further enhancements in fracture properties. This new knowledge will enable true atomic-level engineering to be joined with microscale tailoring to develop the advanced ceramics that will be required for more efficient engines, new electronic device architectures and composites.

A Physics-Based Data-Driven Model for History Matching, Prediction, and Characterization of Unconventional Reservoirs

SPE Journal ◽  
2018 ◽  
Vol 23 (04) ◽  
pp. 1105-1125 ◽  
Author(s):  
Yanbin Zhang ◽  
Jincong He ◽  
Changdong Yang ◽  
Jiang Xie ◽  
Robert Fitzmorris ◽  
...  
Keyword(s):  
History Matching ◽  
Unconventional Reservoirs ◽  
Data Driven ◽  
Linear Flow ◽  
Multiple Data ◽  
Straight Line ◽  
Diagnostic Characteristics ◽  
Ensemble Smoother ◽  
1D Numerical Simulation

Summary We developed a physics-based data-driven model for history matching, prediction, and characterization of unconventional reservoirs. It uses 1D numerical simulation to approximate 3D problems. The 1D simulation is formulated in a dimensionless space by introducing a new diffusive diagnostic function (DDF). For radial and linear flow, the DDF is shown analytically to be a straight line with a positive or zero slope. Without any assumption of flow regime, the DDF can be obtained in a data-driven manner by means of history matching using the ensemble smoother with multiple data assimilation (ES-MDA). The history-matched ensemble of DDFs offers diagnostic characteristics and probabilistic predictions for unconventional reservoirs.

scholarly journals Insights into Multifractal Characterization of Coals by Mercury Intrusion Porosimetry

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4743
Author(s):  
Sijian Zheng ◽  
Yanbin Yao ◽  
Shasha Zhang ◽  
Yong Liu ◽  
Jinhui Yang
Keyword(s):  
Multifractal Analysis ◽  
Mercury Intrusion Porosimetry ◽  
Practical Method ◽  
Unconventional Reservoirs ◽  
Tight Sandstone ◽  
Mercury Intrusion ◽  
The Matrix ◽  
High Mercury ◽  
Heterogeneity Characteristics

Mercury intrusion porosimetry (MIP) as a practical and effective measurement has been widely used in characterizing the pore size distribution (PSD) for unconventional reservoirs (e.g., coals and shales). However, in the process of MIP experiments, the high mercury intrusion pressure may cause matrix compressibility and result in inaccurate estimations of PSD. To get a deeper understanding of the variability and heterogeneity characteristics of the actual PSD in coals, this study firstly corrected the high mercury intrusion pressure data in combination with low-temperature N2 adsorption (LTNA) data. The results show that the matrix compressibility was obvious under the pressure over 24.75 MPa, and the calculated matrix compressibility coefficients of bituminous and anthracite coals range from 0.82 to 2.47 × 10−10 m2/N. Then, multifractal analysis was introduced to evaluate the heterogeneity characteristics of coals based on the corrected MIP data. The multifractal dimension Dmin is positively correlated with vitrinite content, but negatively correlated with inertinite content and mercury intrusion saturation. The multifractal dimension Dmax shows negative relationships with moisture and ash content, and it also emerges as a “U-shaped” trend with efficiency of mercury withdrawal. It is concluded that multifractal analysis can be served as a practical method not only for evaluating the heterogeneity of coal PSDs, but also for other unconventional reservoirs (e.g., shale and tight sandstone).

scholarly journals Physicochemical and Mechanical Characterization of Raffia vinifera Pith

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
N. R. Sikame Tagne ◽  
T. E. Mbou ◽  
O. Harzallah ◽  
D. Ndapeu ◽  
W. Huisken ◽  
...  
Keyword(s):  
Natural Fibers ◽  
Tensile Tests ◽  
Effective Area ◽  
Bending Tests ◽  
Energy Dispersion Spectrometer ◽  
Eds Analysis ◽  
Matrix Properties ◽  
The Matrix ◽  
Imagej Software

In this paper, the physicochemical and mechanical properties of Raffia vinifera pith (RVP) are discussed. Microscopic observations have shown that the structure of the RVP is similar to that of a composite consisting of natural fibers. The effective area ratio of Raffia vinifera (RV) fibers was evaluated along the raffia stem using ImageJ software, and it decreases from the periphery to the center. Energy dispersion spectrometer (EDS) analysis shows that RVP is essentially composed of carbon and oxygen. Densities of RVP and its matrix were determined using Archimedes’ principle and law of mixtures, respectively; from the results obtained, they can be considered as one of the lightest materials. Young’s modulus of RVP has been obtained from tensile and bending tests, while that of matrix has been obtained using the law of mixtures during tensile tests. RVP has better specific properties, and the results of the matrix properties show that we can easily select another matrix which has better properties than the case studied during the elaboration of composites.

A Multiscale Workflow for History Matching in Structured and Unstructured Grid Geometries

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 828-848 ◽  
Author(s):  
E.. Bhark ◽  
A.. Rey ◽  
A.. Datta-Gupta ◽  
B.. Jafarpour
Keyword(s):  
History Matching ◽  
Large Scale ◽  
Preferential Flow ◽  
Ad Hoc ◽  
Grid Cell ◽  
Field Application ◽  
Basis Functions ◽  
Reservoir Model ◽  
Well Pattern ◽  
Permeability Field

Summary We present the development and field application of a workflow for multiscale reservoir-model calibration that seamlessly integrates production data into the reservoir description from the facies to the grid-cell scale. To start with, the permeability field is parameterized using a novel grid-connectivity-based transformation basis that can be applied with any model geometry, including unstructured and corner-point grids. The parameterization basis functions emerge from spectral decomposition of the grid-connectivity Laplacian and are related to the structural harmonics of the grid. To reconcile data with model resolution during history matching, we first use the coarsest-scale basis functions to identify the large-scale variability. Additional smaller-scale basis elements are then adaptively incorporated to successively refine the model to a level supported by data resolution. During refinement, the inclusion of more detailed basis functions into the parameterization is determined by generic modal frequency when the prior model is unavailable or by using prior information when available. In the final step of the workflow, a streamline-based inversion is performed to locally adjust the reservoir model at grid-cell resolution along preferential-flow paths defined during the coarser-scale parameterization. We demonstrate the suitability and effectiveness of the developed workflow through application to an offshore turbidite reservoir with frequent well intervention, including shut-ins and recompletions. The static model has over 300,000 cells, a complex channelized interpretation with faults, four injector/producer pairs with deviated wells, and over eight years of production history, including water cut and pressure data. The grid-connectivity-based parameterization effectively updates the prior regional permeability at scales and in locations warranted by the data, while preserving the geologic continuity and avoiding ad hoc redefinition of regions given the sparse well pattern. The multiscale calibrated-permeability field indicates flow communication previously unrecognized in static geologic interpretation or manual history matching.

Comprehensive characterization investigation of multiple time-varying rock-fluid properties in waterflooding development

2021 ◽  
pp. 1-18
Author(s):  
Jingqi Lin ◽  
Ruizhong Jiang ◽  
Zeyang Shen ◽  
Qiong Wang ◽  
Yongzheng Cui ◽  
...  
Keyword(s):  
History Matching ◽  
Absolute Permeability ◽  
Multiple Time ◽  
Time Varying ◽  
Reservoir Model ◽  
Oil Viscosity ◽  
Fluid Properties ◽  
Black Oil Model ◽  
Comprehensive Characterization

Abstract In this paper, the characterization parameter ‘effective displacement flux’ is employed to describe the flushing intensity and a new numerical simulator in which the rock-fluid properties considered functions of the effective displacement flux is developed based on the black oil model. Additionally, a conceptual reservoir model is established to validate the effective characterization of the time-varying mechanisms: the time-varying oil viscosity can characterize the viscous fingering of the water phase the time-varying absolute permeability can present the aggravation of reservoir heterogeneity, the alteration of wettability is characterized with the time-varying relative permeability, and the ultimate recovery will increase with the combined effect of all three time-varying factors. Eventually, the new simulator is applied to the simulation of an actual waterflooding reservoir to illustrate the assistance in history matching. The simulation results of our simulator can readily match the history data, which proves that the consideration of comprehensive time-varying rock-fluid properties can significantly improve the accuracy during the numerical simulation of waterflooding reservoirs.

Simulation of Matrix/Fracture Interaction in Low-Permeability Fractured Unconventional Reservoirs

SPE Journal ◽  
2018 ◽  
Vol 23 (04) ◽  
pp. 1389-1411 ◽  
Author(s):  
D. Y. Ding ◽  
N.. Farah ◽  
B.. Bourbiaux ◽  
Y.-S.. -S. Wu ◽  
I.. Mestiri
Keyword(s):  
Transient Flow ◽  
Unconventional Reservoirs ◽  
Hydraulic Fractures ◽  
Low Permeability ◽  
State Matrix ◽  
Discrete Fracture Model ◽  
Matrix Fracture ◽  
Discrete Fracture ◽  
The Matrix ◽  
Fracture Interaction

Summary Unconventional reservoirs, such as shale-gas or tight oil reservoirs, are generally highly fractured (including hydraulic fractures and stimulated and nonstimulated natural fractures of various sizes) and embedded in low-permeability formations. One of the main production mechanisms in unconventional reservoirs is the flow exchange between matrix and fracture media. However, because of extremely low matrix permeability, the matrix/fracture exchange is very slow and the transient flow may last several years to tens of years, or almost the entire production life. The commonly used dual-porosity (DP) modeling approach involves a computation of pseudosteady-state matrix/fracture transfers with homogenized fluid and flow properties within the matrix medium. This kind of model clearly fails to handle the long-lasting matrix/fracture interaction in very-low-permeability reservoirs, especially for multiphase flow with phase-change problems. Moreover, a DP model is not adapted for the simulation of matrix/fracture exchange when fractures are described by a discrete-fracture network (DFN). This paper presents an embedded discrete-fracture model (EDFM) dependent on the multiple-interacting-continua (MINC) proximity function to overcome this insufficiency of the conventional DP model.

A Comprehensive Reservoir Simulator for Unconventional Reservoirs That Is Based on the Fast Marching Method and Diffusive Time of Flight

SPE Journal ◽  
2016 ◽  
Vol 21 (06) ◽  
pp. 2276-2288 ◽  
Author(s):  
Yusuke Fujita ◽  
Akhil Datta-Gupta ◽  
Michael J. King
Keyword(s):  
Time Of Flight ◽  
Unconventional Reservoirs ◽  
Hydraulic Fractures ◽  
Fast Marching Method ◽  
Simulation Approach ◽  
Fast Marching ◽  
Drainage Volume ◽  
Marching Method ◽  
Diffusive Time

Summary Modeling of fluid flow in unconventional reservoirs requires accurate characterization of complex flow mechanisms because of the interactions between reservoir rock, microfractures, and hydraulic fractures. The pore-size distribution in shale and tight sand reservoirs typically ranges from nanometers to micrometers, resulting in ultralow permeabilities. In such extremely low-permeability reservoirs, desorption and diffusive processes play important roles in addition to heterogeneity-driven convective flows. For modeling shale and tight oil and gas reservoirs, we can compute the well-drainage volume efficiently with a fast marching method (FMM) and by introducing the concept of “diffusive time of flight” (DTOF). Our proposed simulation approach consists of two decoupled steps—drainage-volume calculation and numerical simulation with DTOF as a spatial coordinate. We first calculate the reservoir drainage volume and the DTOF with the FMM, and then the numerical simulation is conducted along the 1D DTOF coordinate. The approach is analogous to streamline modeling whereby a multidimensional simulation is decoupled to a series of 1D simulations resulting in substantial savings in computation time for high-resolution simulation. However, instead of a “convective time of flight” (CTOF), a DTOF is introduced to model the pressure-front propagation. For modeling physical processes, we propose triple continua whereby the reservoir is divided into three different domains: microscale pores (hydraulic fractures and microfractures), nanoscale pores (nanoporous networks), and organic matter. The hydraulic fractures/microfractures primarily contribute to the well production, and are affected by rock compaction. The nanoporous networks contain adsorbed gas molecules, and gas flows into fractures by convection and Knudsen diffusion processes. The organic matter acts as the source of gas. Our simulation approach enables high-resolution flow characterization of unconventional reservoirs because of its efficiency and versatility. We demonstrate the power and utility of our approach with synthetic and field examples.

Workflow to Optimize Cluster Spacing Design of Horizontal Multistage Fractured Well in Unconventional Source Rock

2021 ◽  
Author(s):  
Rabah Mesdour ◽  
Moemen Abdelrahman ◽  
Abdulbari Alhayaf
Keyword(s):  
Hydraulic Fracturing ◽  
Source Rock ◽  
Unconventional Reservoirs ◽  
Analytical Models ◽  
Sensitivity Analyses ◽  
Reservoir Modeling ◽  
Hydraulic Fractures ◽  
Reservoir Model ◽  
Well Productivity ◽  
Horizontal Drilling

Abstract Horizontal drilling and multistage hydraulic fracturing applied in unconventional reservoirs over the past decade to create a large fracture surface area to improve the well productivity. The combination of reservoir quality with perforation cluster spacing and fracture staging are keys to successful hydraulic fracturing treatment for horizontal wells. The objective of this work is to build and calibrate a dynamic model by integrating geologic, hydraulic fracture, and reservoir modeling to optimize the number of clusters and other completion parameters for a horizontal well drilled in the source rock reservoir using simulation and analytical models. The methodology adopted in this study covers the integration of geological, petrophysical, and production data analysis to evaluate reservoir and completion qualities and quantify the heterogeneity and the perforation clusters number required within a frac stage. Assuming all perforation clusters are uniformly distributed within a stage. The hydraulic planer fracture attributes assumed and the surface production measurement together with the production profile were used to calibrate the reservoir model. The properties of the Stimulated Reservoir Volume "SRV" were defined after the final calibration using reservoir model including hydraulic fractures. The calibrated reservoir model was used to carry out sensitivity analyses for cluster spacing optimization and other completion parameters considering the surface and reservoir constraints. An optimum cluster spacing was observed based on the Estimated Ultimate Recovery "EUR" of the subject well by reservoir properties. The final results based on 70% of perforation clusters contribution to production observed from PLT log, and the results of this study were implemented. Afterwards, another study has been undertaken to increasing the stimulation effectiveness and maximizing the number of perforation clusters contributing to productivity as an area for improvement to engineering the completion design. The methodology adopted in this study identifies the most important parameters of completion affecting well productivity for specific unconventional reservoirs. This study will help to engineer completion design, improve cluster efficiency, reduce cost and increase well EUR for the development phase.

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

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