scholarly journals Description of Fracture Network of Hydraulic Fracturing Vertical Wells in Unconventional Reservoirs

2021 ◽  
Vol 9 ◽  
Author(s):  
Jinghua Liu ◽  
Mingjing Lu ◽  
Guanglong Sheng
Keyword(s):  
Flow Rate ◽  
Early Stage ◽  
Fractal Theory ◽  
Fracture Network ◽  
Unconventional Reservoirs ◽  
Box Dimension ◽  
Vertical Wells ◽  
Reservoir Permeability ◽  
Fractal Index ◽  
Volume Fracturing

Based on the distribution of complex fractures after volume fracturing in unconventional reservoirs, the fractal theory is used to describe the distribution of volume fracture network in unconventional reservoirs. The method for calculating the fractal parameters of the fracture network is given. The box dimension method is used to analyze a fracturing core, and the fractal dimension is calculated. The fractal index of fracture network in fracturing vertical wells are also firstly calculated by introducing an analysis method. On this basis, the conventional dual-media model and the fractal dual-media model are compared, and the distribution of reservoir permeability and porosity are analyzed. The results show that the fractal porosity/permeability can be used to describe the reservoir physical properties more accurately. At the same time, the flow rate calculating by conventional dual-media model and the fractal dual-media model were calculated and compared. The comparative analysis found that the flow rate calculated by the conventional dual-media model was relatively high in the early stage, but the flow rate was not much different in the later stage. The research results provide certain guiding significance for the description of fracture network of volume fracturing vertical well in unconventional reservoirs.

scholarly journals Research on numerical method for evaluation of vertical well volume fracturing effect based on production data and well test data

2021 ◽  
Vol 11 (4) ◽  
pp. 1855-1863
Author(s):  
Debin Xia ◽  
Zhengming Yang ◽  
Daolun Li ◽  
Yapu Zhang ◽  
Xinli Zhao ◽  
...  
Keyword(s):  
Numerical Model ◽  
Test Data ◽  
Fracture Zone ◽  
Fracture Network ◽  
Production Data ◽  
Well Test ◽  
Vertical Wells ◽  
Equivalent Permeability ◽  
Main Fracture ◽  
Volume Fracturing

AbstractVolume transformation technology has become a key technology for developing low-permeability/tight oil and gas reservoirs. Evaluating the post-fracturing effect is very important for the development plan formulation and fracturing plan evaluation. In this paper, the vicinity of the main fracture is divided into the main fracture zone and the secondary fracture zone. The main fracture with infinite conductivity and the branch fracture with increased permeability are used to describe the transformation area. Based on this physical model, a numerical model considering the nonlinear seepage characteristics of the reservoir, stress sensitivity, wellbore storage and skin effects was established. Based on this numerical model, a comprehensive evaluation method for the fracturing effect of volume modification of vertical wells based on well test data and production data was established and this method was applied to three typical vertical wells. The results show that conventional vertical fracturing vertical wells can only form a single primary fracture and the range of equivalent permeability increase is very small. Volume fracturing can form a fracture network composed of primary fractures and secondary fractures, and increase the equivalent permeability of the fracture network area. The fracture half-length, equivalent permeability and reconstruction area of the volume fracturing well are dynamically changing and gradually decrease with the increase in production time and the fracturing effect becomes weak until it fails.

scholarly journals Volume fracturing technology of unconventional reservoirs: Connotation, design optimization and implementation

2012 ◽  
Vol 39 (3) ◽  
pp. 377-384 ◽  
Author(s):  
Qi WU ◽  
Yun XU ◽  
Xiaoquan WANG ◽  
Tengfei WANG ◽  
Shouliang ZHANG
Keyword(s):  
Design Optimization ◽  
Unconventional Reservoirs ◽  
Volume Fracturing

Research of Coal Pores and Integrity Evaluation Method Based on Fractal Theory

2014 ◽  
Vol 670-671 ◽  
pp. 258-262 ◽  
Author(s):  
Ji Li ◽  
Xin Wu
Keyword(s):  
Fractal Dimension ◽  
Coal Sample ◽  
Evaluation Method ◽  
Structural Integrity ◽  
Gas Adsorption ◽  
Fractal Theory ◽  
Physical And Mechanical Properties ◽  
Box Dimension ◽  
Sem Images ◽  
Sem Image

Coal is a natural porous media, its porosity and structural integrity influenced the gas adsorption and desorption characteristics greatly, as well as physical and mechanical properties of coal. Scanning electron microscopy (SEM) is applied to acquire SEM image of four kinds of coal samples at different zoom levels, and the box dimension can be worked out based on the pore preprocessing of SEM images. Then, the numerical value of box dimension is used to describe the development degree of the four kinds of coal sample and four development degrees’ sequence. At last, the intrinsic relevance between fractal dimension and other parameters is analyzed through mathematic method. The results show as follows: coal sample has self-similarity characteristic; the fractal dimension is related to both the total number of pores and porosity degree; the data of the coal pore, analyzed through fractal dimension, are consistent with that through traditional method; what’s more, fractal dimension has more advantages in describing accuracy and simplicity.

The Performance Evaluation of Old Well after SRV in Ordos Basin Tight Oil Reservoir

2014 ◽  
Author(s):  
H.. Wang ◽  
X.. Liao ◽  
H.. Ye ◽  
X.. Zhao ◽  
C.. Liao ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Ordos Basin ◽  
Fracture Network ◽  
Water Flooding ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Well Test ◽  
Stimulated Reservoir Volume ◽  
Tight Oil Reservoir ◽  
Volume Fracturing

Abstract The technology of Stimulated reservoir volume (SRV) has been the key technology for unconventional reservoir development, it can create fracture network in formation and increase the contact area between fracture surface and matrix, thus realizing the three-dimensional stimulation and enhancing single well productivity and ultimate recovery. In China, the Ordos Basin contains large areas of tight oil reservoir with the porosity of 2~12 % and permeability of 0.01~1 mD. The most used development mode is conventional fracturing and water flooding, which is different from the natural depletion mode in oversea, but the development effect is still unfavorable. The idea of SRV is proposed in nearly two years in Changqing Oilfield. SRV measures are implemented in some old wells in tight oil formation. It is a significant problem that should be solved urgently about how to evaluate the volume fracturing effect. Based on the real cases of old wells with SRV measures, the microseismic monitoring is used to analyze the scale of formation stimulation and the complexity of fracture network after volume fracturing; the numerical well test and production data analysis (PDA) are selected to explain the well test data, to analyze the dynamic data, and to compare the changes of formation parameters, fluid parameters and plane streamlines before and after volume fracturing; then the interpretation results of well test with the dynamic of oil and water wells are combined to evaluate the stimulation results of old wells after SRV. This paper has presented a set of screening criteria and an evaluation method of fracturing effect for old well with SRV in tight oil reservoir. It will be helpful to the selection of candidate well and volume fracturing operation in Ordos Basin tight oil reservoir. It should be noted that the evaluation method mentioned in the paper can be expanded to volume stimulation effect evaluation in other unconventional reservoirs, such as tight gas, shale gas and so on.

A Leap into Automation for Advanced Fracture Characterization

2021 ◽  
Author(s):  
Radhika Patro ◽  
Manas Mishra ◽  
Hemlata Chawla ◽  
Sambhaji Devkar ◽  
Mrinal Sinha ◽  
...  
Keyword(s):  
Machine Learning ◽  
Fracture Network ◽  
Unconventional Reservoirs ◽  
Machine Learning Techniques ◽  
Coal Bed ◽  
Fracture Characterization ◽  
Learning Techniques ◽  
Macro Scale ◽  
Porosity And Permeability ◽  
Depth Of Investigation

Abstract Fractures are the prime conduits of flow for hydrocarbons in reservoir rocks. Identification and characterization of the fracture network yields valuable information for accurate reservoir evaluation. This study aims to portray the benefits and limitations for various existing fracture characterization methods and define strategic workflows for automated fracture characterization targeting both conventional and unconventional reservoirs separately. While traditional seismic provides qualitative information of fractures and faults on a macro scale, acoustics and other petrophysical logs provide a more comprehensive picture on a meso and micro level. High resolution image logs, with shallow depth of investigation are considered the industry standard for analysis of fractures. However, it is imperative to understand the framework of fracture in both near and far field. Various reservoir-specific collaborative workflows have been elucidated for a consistent evaluation of fracture network, results of which are further segregated using class-based machine learning techniques. This study embarks on understanding the critical requirements for fracture characterization in different lithological settings. Conventional reservoirs have good intrinsic porosity and permeability, yet presence of fractures further enhances the flow capacity. In clastic reservoirs, fractures provide an additional permeability assist to an already producible reservoir. In carbonate reservoirs, overall reservoir and production quality exclusively depends on presence of extensive fracture network as it quantitatively controls the fluid flow interactions among otherwise isolated vugs. Devoid of intrinsic porosity and permeability, the presence of open-extensive fractures is even more critical in unconventional reservoirs such as basement, shale-gas/oil and coal-bed methane, since it demarcates the reservoir zone and defines the economic viability for hydrocarbon exploration in reservoirs. Different forward modeling approaches using the best of conventional logs, borehole images, acoustic data (anisotropy analysis, borehole reflection survey and stoneley waveforms) and magnetic resonance logs have been presented to provide reservoir-specific fracture characterization. Linking the resolution and depth of investigation of different available techniques is vital for the determination of openness and extent of the fractures into the formation. The key innovative aspect of this project is the emphasis on an end-to-end suitable quantitative analysis of flow contributing fractures in different conventional and unconventional reservoirs. Successful establishment of this approach capturing critical information will be the stepping-stone for developing machine learning techniques for field level assessment.

scholarly journals An evaluation method of volume fracturing effects for vertical wells in low permeability reservoirs

2020 ◽  
Vol 47 (2) ◽  
pp. 441-448
Author(s):  
Anshun ZHANG ◽  
Zhengming YANG ◽  
Xiaoshan LI ◽  
Debin XIA ◽  
Yapu ZHANG ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Low Permeability ◽  
Vertical Wells ◽  
Volume Fracturing ◽  
Low Permeability Reservoirs

Sensitivity of Digital Thermal Monitoring Parameters to Reactive Hyperemia

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Mohammad W. Akhtar ◽  
Stanley J. Kleis ◽  
Ralph W. Metcalfe ◽  
Morteza Naghavi
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Vascular Reactivity ◽  
Early Stage ◽  
Reactive Hyperemia ◽  
Assessment Tools ◽  
Functional Evaluation ◽  
Thermal Monitoring ◽  
Essential Components ◽  
Baseline Flow

Both structural and functional evaluations of the endothelium exist in order to diagnose cardiovascular disease (CVD) in its asymptomatic stages. Vascular reactivity, a functional evaluation of the endothelium in response to factors such as occlusion, cold, and stress, in addition to plasma markers, is the most widely accepted test and has been found to be a better predictor of the health of the endothelium than structural assessment tools such as coronary calcium scores or carotid intima-media thickness. Among the vascular reactivity assessment techniques available, digital thermal monitoring (DTM) is a noninvasive technique that measures the recovery of fingertip temperature after 2–5 min of brachial occlusion. On release of occlusion, the finger temperature responds to the amount of blood flow rate overshoot referred to as reactive hyperemia (RH), which has been shown to correlate with vascular health. Recent clinical trials have confirmed the potential importance of DTM as an early stage predictor of CVD. Numerical simulations of a finger were carried out to establish the relationship between DTM and RH. The model finger consisted of essential components including bone, tissue, major blood vessels (macrovasculature), skin, and microvasculature. The macrovasculature was represented by a pair of arteries and veins, while the microvasculature was represented by a porous medium. The time-dependent Navier–Stokes and energy equations were numerically solved to describe the temperature distribution in and around the finger. The blood flow waveform postocclusion, an input to the numerical model, was modeled as an instantaneous overshoot in flow rate (RH) followed by an exponential decay back to baseline flow rate. Simulation results were similar to clinically measured fingertip temperature profiles in terms of basic shape, temperature variations, and time delays at time scales associated with both heat conduction and blood perfusion. The DTM parameters currently in clinical use were evaluated and their sensitivity to RH was established. Among the parameters presented, temperature rebound (TR) was shown to have the best correlation with the level of RH with good sensitivity for the range of flow rates studied. It was shown that both TR and the equilibrium start temperature (representing the baseline flow rate) are necessary to identify the amount of RH and, thus, to establish criteria for predicting the state of specific patient’s cardiovascular health.

Study on Fractal Characteristics of Acoustic Emission in Circular Double-Layer Stirrup Confined Concrete

2014 ◽  
Vol 578-579 ◽  
pp. 359-368 ◽  
Author(s):  
Peng Fei Geng ◽  
Lin Zhu Sun ◽  
Fang Yang ◽  
Wei Li
Keyword(s):  
Acoustic Emission ◽  
Fractal Dimension ◽  
Double Layer ◽  
Fractal Theory ◽  
Equivalent Stress ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Box Dimension ◽  
Emission Parameter ◽  
Fractal Characteristics

Vertical bearing capacity experiments were conducted with circular double-layer stirrup confined concrete columns as study objects, data acquisition was carried out using acoustic emission (AE) equipment and the AE parameters and graphs acquired during the experiments were analyzed to obtain the damage evolution of steel reinforced concrete columns under compression. The correlation between fractal dimension of AE graphs and curve was studied using the fractal theory, and the results show that the AE parameter graphs have fractal characteristics and the box dimension of each AE parameter graph constantly increases with the increase in stress, with a positive correlation exhibited between the fractal dimension and stress level. The loss variable expressed with fractal dimension was defined to establish actual equivalent stresses and the equivalent stress curves and experimental curves were compared; the results show that the fractal dimension of acoustic emission parameter graph can characterize the damage laws of the concrete member.

Sign in / Sign up

Export Citation Format

Share Document