Fracture Shape Research Articles

PERPATAHAN FATIK MATERIAL ALUMINIUM 2024-T3 DENGAN PENGELASAN FSW

Resilient, machine processed, shapped aluminium using pulling power for pure aluminium with 4-5kgf/mm2. Aluminium fusion with series 2024-T3 is a metal fusion whose low weldability so it is very difficult to be conducted the welding process because it tends to occur hot cracking or being porous, and precipitation hardening when conducting welding process due to segregation of copper (Cu) fusion subtance. One of welding method to obtain the good aluminium welding result is by using FSW (friction stir welding). The purpose of this research is to find out the shape and type of fracture on aluminium fusion with FSW welding by dealing TTT. The fracture is created from fatik substance test. The reserach method was conducted by welding of plate aluminium fusion 2024-T3 using FSW technique by dealing transient thermal tensioning (TTT). Transient thermal was conducted by resigning heater line with weld tool/pin. The speed of determined FSW welding was 11 mm/minutes and 1200 rpm. The conducted test was fatigue test and factografi test with SEM. The result of the reserach shows that the number of fatik test cycle is 765.250 with sigmoidal curve visually. Then, the result of fractography using SEM shows that the occured fracture is brittle.

Apparent Toughness Anisotropy Induced by “Roughness” of In-Situ Stress: A Mechanism That Hinders Vertical Growth of Hydraulic Fractures and Its Simplified Modeling

Summary The height growth of a hydraulic fracture is known to be affected by many factors that are related to the layered structure of sedimentary rocks. Although these factors are often used to qualitatively explain why hydraulic fractures usually have well–bounded height growth, most of them cannot be directly and quantitatively characterized for a given reservoir to enable a priori prediction of fracture–height growth. In this work, we study the role of the “roughness” of in–situ–stress profiles, in particular alternating low and high stress among rock layers, in determining the tendency of a hydraulic fracture to propagate horizontally vs. vertically. We found that a hydraulic fracture propagates horizontally in low–stress layers ahead of neighboring high–stress layers. Under such a configuration, a fracture–mechanics principle dictates that the net pressure required for horizontal growth of high–stress layers within the current fracture height is significantly lower than that required for additional vertical growth across rock layers. Without explicit consideration of the stress–roughness profile, the system behaves as if the rock is tougher against vertical propagation than it is against horizontal fracture propagation. We developed a simple relationship between the apparent differential rock toughness and characteristics of the stress roughness that induce equivalent overall fracture shapes. This relationship enables existing hydraulic–fracture models to represent the effects of rough in–situ stress on fracture growth without directly representing the fine–resolution rough–stress profiles.

Numerical model of fracture growth in hydraulic re-fracturing

Simulation of fracture propagation with FEM method generates the need of re-meshing to provide more accurate results. This raises a question of determining the direction and criterion of mesh modification. In the case of general-purpose CAE-packages, we deal with a stationary mesh, and the fracture path is usually represented as a chain of elements with degraded properties. The algorithm proposed in this paper is based on the ANSYS Mechanical APDL language for stepwise geometry reconstruction and mesh modification in accordance with the current configuration of a growing fracture and provides a more accurate description of its shape. The fracture propagation process is divided into stages. Each subsequent stage differs from the previous one by the fracture shape modified due to the crack length increment in the calculated direction. To check the adequacy of the model, an experiment on fracture propagation in glass specimens with an initial notching under uniaxial compression was performed. The laboratory experiments were carried out to determine the fracture toughness of rocks. The developed numerical model has been used to solve the problem of re-fracturing for different stress anisotropy in the oil-bearing rock formation.

Numerical simulation of borehole Stoneley wave reflection by a fracture based on variable grid spacing method

In this paper, the finite difference method is used to model the Stoneley wave reflection by a horizontal fracture in a borehole. The fracture shape is described by some finite difference grids. Therefore, the fracture aperture can be varied in the radial direction, thus extending previous researches on the assumption that the fracture aperture is constant throughout the fracture. Finite difference grids can also be used to describe a fracture which extends a finite distance in the radial direction. In addition, the finite difference algorithm can deal with the problem of inhomogeneous formation. Therefore, it allows the variation of formation elasticity in the model. Fine grids are needed to describe the small fracture aperture, and variable grid spacing is employed by finite difference method to improve computational efficiency. The Stoneley wave propagation is simulated by the variable grid spacing finite difference method in several models with variable fracture aperture, finite extension fracture and models with heterogeneous formation. The variable grid spacing finite difference method is validated through a comparison with real axis integration method and the analytical method. We get some conclusions by simulating and investigating effects of the variation of fracture aperture, the fracture of finite extension and inhomogeneity of formation on the Stoneley wave reflection. Although the fracture aperture changes along the fracture extension direction, the reflection coefficient of Stoneley wave is mainly controlled by the fracture aperture near the borehole. The Stoneley wave in the fracture is reflected back into the borehole, by the tip of finite extension fracture, which results in some notches in the reflection coefficient curve. If the Stoneley wave propagates from the formation with small elastic modulus to the formation with large elastic modulus, the reflection coefficient of Stoneley wave will be larger than that of homogeneous model with small elastic modulus. And if Stoneley wave propagates from the formation with large elastic modulus to the formation with small elastic modulus, the reflection coefficient of Stoneley wave will be smaller that of homogeneous model with large elastic modulus. These results provide some basis for the use of Stoneley wave to detect the fracture properties in formation.

Experimental and numerical investigation on the response of stiffened panels subjected to lateral impact considering material failure criteria

A series of experiments have been conducted to investigate the dynamic response of stiffened panels. The uniaxial tension experiments and the dynamic experiments were conducted to obtain the material characterization. The falling weight experiments were conducted to study the dynamic response of the stiffened panels. A dynamic BWH criterion which combines the BWH criterion and the Cowper-Symonds model is proposed to evaluate the material failure. The scaled constant strain (CS) criterion can decrease the influence of mesh size and improve the accuracy of the simulations. These two different criteria are applied in the simulation models and the simulation results are compared with the experiments. The simulations of the experiments are carried out using the explicit solver of the finite element software package Abaqus. The dynamic BWH criterion is implemented in the numerical simulation using user material subroutine (VUMAT). The simulation results show that the dynamic BWH criterion is better consistent with the experimental results than the scaled CS criterion. Because the influence of stress state and strain rate on material failure has been considered in the dynamic BWH criterion. The formation mechanism of different fracture shapes of the stiffened panels is discussed.

The effect of stress distribution on the shape and direction of hydraulic fractures in layered media

In this study, the propagation of a hydraulic fracture in a three-layer medium is investigated using a robust finite element method. The top and bottom layers have similar properties, while the soft middle layer has variable thickness and stiffness. Both two-dimensional plane-strain and three-dimensional models are used to evaluate the vertical and lateral growth of the fracture, initiated from the bottom layer. In 2D model, the competition between the gravity forces and the stress concentration at the layer boundary dictates whether the fracture grows upward or downward, while in the 3D model, the lateral growth of the fracture is also captured. Results from the 2D model show that in majority of cases (6 out of 9) the fracture reaches to the middle layer, and due to the lower minimum principal stress in this layer, an extensive propagation occurs in this layer. When the lateral growth is considered utilising the 3D model, depending on the stress concentration and the position of the fracture in the bottom layer, the downward or lateral growth may become dominant. Thus, the geometry of the fracture can vary between a long and narrow shape towards a round shape. The lateral growth of fractures in the 3D model undermines the suitability of 2D plane-strain model results.

Shock-induced damage and dynamic fracture in cylindrical bodies submerged in liquid

Understanding the response of solid materials to shock loading is important for mitigating shock-induced damages and failures, as well as advancing the beneficial use of shock waves for material modifications. In this paper, we consider a representative brittle material, BegoStone, in the form of cylindrical bodies and submerged in water. We present a computational study on the causal relationship between the prescribed shock load and the resulting elastic waves and damage in the solid material. A recently developed three-dimensional computational framework, FIVER, is employed, which couples a finite volume compressible fluid solver with a finite element structural dynamics solver through the construction and solution of local, one-dimensional fluid-solid Riemann problems. The material damage and fracture are modeled and simulated using a continuum damage mechanics model and an element erosion method. The computational model is validated in the context of shock wave lithotripsy and the results are compared with experimental data. We first show that after calibrating the growth rate of microscopic damage and the threshold for macroscopic fracture, the computational framework is capable of capturing the location and shape of the shock-induced fracture observed in a laboratory experiment. Next, we introduce a new phenomenological model of shock waveform, and present a numerical parametric study on the effects of a single shock load, in which the shock waveform, magnitude, and the size of the target material are varied. In particular, we vary the waveform gradually from one that features non-monotonic decay with a tensile phase to one that exhibits monotonic decay without a tensile phase. The result suggests that when the length of the shock pulse is comparable to that of the target material, the former waveform may induce much more significant damage than the latter one, even if the two share the same magnitude, duration, and acoustic energy.

Effect of Alkalization Treatment on The Tensile Strength and Interface Character Matrix-Fibber of Bamboo Petung (Dendrocalamus Asper) Reinforced Polyester Resin Composite

The purpose of this study is to determine the alkalization process effect of bamboo petung fiber (Dendrocalamus Asper) on the Tensile strength of Polyester composite reinforced with bamboo petung fiber. The alkalization process is expected to increase the bond between the automatic and the fiber which in turn can increase the tensile strength of the composite. In this study NaOH was used as an alkaline substance. NaOH is an alkali commonly used as a substance for the alkalization process in various natural fibers for natural composite reinforcing material. Alkalization was done by soaking the fiber into NaOH solution at room temperature and time variation for 1 hour, 2 hours, and 3 hours. After the alacalization process, the fiber was processed to be made into a composite with a polyester matrix with the direction of unidirectional fiber orientation. The process of making composites used vacuum infusion method. Before being used as reinforcing fibers, petung bamboo fiber composites were tested for single fiber tensile strength both after alkalization treatment and fiber before alkalization process. Composite tensile testing was conducted on all variations of both composites with fibers before Alkalization and composite after the alkalization process by using ASTM D638-03 standard. Scaning Electronics Microscope (SEM) was also conducted to observe the morphology of fibers before and after alkalization, besides that SEM was also used to determine the fracture shape of polyester composite reinforced with bamboo petung fiber. From the Tensile testing conducted on single fiber and composite, it was obtained results that either the single fibers strength or composites decreased with increasing NaOH soaking time.

Slip perturbation during fault reactivation by a fluid injection

Slip orientation inferred from fault striae or focal mechanism datasets is commonly used in stress inversion methods based on the Wallace-Bott hypothesis. The hypothesis postulates that slip on a fault plane is collinear with the orientation of the resolved shear stress. It is valid for a single planar fault subjected to a homogeneous far-field stress. However, the experimental displacement data from an induced fault reactivation experiment, conducted in the Mont Terri rock laboratory, Switzerland, indicated multiple triggered slip orientations, thereby preventing application of the above inversion method. We present numerical and analytical results of slip on a reactivated fracture with a non-uniform fluid pressure distribution. Using these models, we evaluate the reasons for the inconsistency of our observations and the traditional Wallace-Bott hypothesis and test the physical effects of various parameters on fault slip. In the fully coupled hydromechanical numerical model (three-dimensional distinct element method), fluid pressure at a point on the fault surface is increased stepwise (assumed planar and singular) until shear reactivation of the fault is induced. We studied two different models with high and low fault plane stiffness to represent hard and soft rock masses, respectively. The model shows that high fault stiffness preserves the planarity of the fault plane, while low fault stiffness permits dilation and morphological changes of the fracture related to fluid pressure diffusion. The highest slip perturbation was observed in the low stiffness model due to the change of the fracture shape, controlled by the non-uniform pressure distribution. The Eshelby analytical solution confirmed that the more the fracture is dilated, the more the corresponding resolved shear stress is perturbed. Additionally, when compared to dilation and fault aperture, the friction angle has the most influence on the angular difference between geomechanical slip vectors and resolved shear stress.

On the estimation of the elastoplastic work needed to initiate crack tearing

Plastic zones (pz) ahead of crack tips are obtained by incremental elastoplastic (EP) finite element (FE) 3D calculations for cracked components with relatively high and low transversal constraints, considering all effects associated with their geometry and loading conditions. Contrary to what is assumed in traditional Fracture Mechanics estimates, pz sizes and shapes do not depend only on the given crack driving force K or J. They depend as well on usually neglected geometric and load parameters such as the component width-to-thickness W/B, the crack size-to-component width a/W, and in particular the nominal stress-to-yield strength σn/SY ratios. Since damage ahead of the crack front depends on the plastic work spent inside the pz, this fact can have a major importance in practical applications, including in fatigue and in EP fracture estimates. This work proposes a methodology for evaluating pz volumes based on a sub-modeling FE analysis that uses the influence volume around a plastified Gauss integration point, instead of the entire plastified FE. This technique is then used to estimate the resistance to crack tearing initiation, assuming it can be obtained from the EP work spent inside the pz. Such estimates are validated using the ratio of experimental fracture toughness at the threshold of crack tearing for different W/B, a/W, and σn/SY combinations.

Study on the Size Effect of Fracture Intersections Based on the Fractal Theory

The geometrical complexity of the fracture space in a rock mass makes the study of the seepage characteristics of fractured rock masses very challenging. Therefore, the study of size effect of fracture intersections, which is the basic fracture shape of fractured rock, can guide the research of fracture seepage. In this context, this paper used FLUENT software to perform a two-dimensional numerical analysis of seepage characteristics at fracture intersection of nine different sizes and analyzed the effect of the intersection size on the fluid pattern and its fractal dimension and split-flow characteristics. The results show that, on the whole, the fractal dimension of the fluid pattern first increased and then decreased, then increased and decreased again with the flow of fluid. The critical point that determined whether fluid would flow out of horizontal fractures was a/b = 0.15; beyond this value, fluid would flow out of three pressure outlets, with flow out of horizontal fractures being higher than out of longitudinal fractures. a/b = 7 was the critical point that determined whether fluid would flow out of longitudinal fractures; at greater values, fluid would flow out of both horizontal fractures and would be far greater than longitudinal flow.

Viability of Gas-Injection EOR in Eagle Ford Shale Reservoirs

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191673, “Dynamic Data Analysis With New Automated Work Flows for Enhanced Formation Evaluation,” by Safian Atan, SPE, Arashi Ajayi, Matt Honarpour, Edward Turek, SPE, Eric Dillenbeck, and Cheryl Mock, BHP, and Mahmood Ahmadi and Carlos Pereira, MI3 Petroleum Engineering, prepared for the 2018 SPE Annual Technical Conference and Exhibition, Dallas, 24–26 September. The paper has not been peer reviewed. Gas-injection huff ’n’ puff enhanced-oil-recovery (EOR) techniques have the potential to improve liquid hydrocarbon recovery in ultratight, unconventional reservoirs. This paper studies the technical and economic viability of this EOR technique in Eagle Ford shale reservoirs using natural gas injection, generally after some period of primary depletion, typically through long, hydraulically fractured horizontal-reach wells. Reservoir-Analysis Work Flow Model Description. A compositional, fine-scale, dual-porosity, dual-permeability, symmetry-element numerical model was used in this study to model the current primary depletion and the EOR huff ’n’ puff process. In this study, the element of symmetry, which represents the bottom half of a cluster within a fracturing stage, is being extended to include three wells to allow the investigation of the effect of interference and containment on pad-level cyclic-gas-injection deployment. Production and injection of the entire well come from all active stages in each well, with equal weighting. The production and the injection for each cluster in every well are calculated proportionally by use of these assumptions. Model Input. The complete paper describes the critical input for the numerical model, including fracture half-length and fracture height, shape factor, absolute and relative permeability, and pressure/volume/temperature (PVT). History-Matching Work Flow. Because the history-matching solution is known to be highly nonunique, a comprehensive probabilistic approach was used to identify the realistic solution space. To facilitate this process, the authors used a three-step approach: Identify the solution space through parametric study. Perform combinatorial analysis of predetermined variables and understand available solutions within the solution space. Fine-tune history matching to identify the correct combination of parameters for probable solutions. Characterizing the Performance of Cyclic Natural-Gas Injection The compositional fluid-flow analysis of the combined sample of the separator liquid and gas at reservoir conditions indicated a volatile oil in the reservoir. To evaluate the phase behavior of the mixture, the original oil and the gas supplied for injection purposes were mixed at different ratios. For each mixture, the calibrated equation of state (EOS) is used to evaluate the resulting phase diagram and fluid properties by modeling a constant-composition-expansion experiment at reservoir conditions. The 1979 Peng-Robinson EOS with nine components was used to model the PVT changes resulting from the composition changes related to each injection ratio. As the composition changes, the phase behavior and the fluid properties also change. The fluid system in the reservoir gradually changed from a volatile oil to a gas condensate. Results show that when injected-gas makeup is 20% or greater, the phase behavior changes from volatile oil to gas condensate. When the mixture consists of more than 70% injected gas, at any pressure below 6,000 psi, there is a possibility that condensation can occur.

Damage Model Test of Prestressed T-Beam Under Explosion Load

Bridge is an important infrastructure in road traffic, which may bear the accidental load of terrorist attacks and transportation accidents and explosions in its life cycle. In this paper, three groups of prestressed T-beam model tests were carried out in response to the terrorist explosion on the bridge deck. The results show that with the increase of explosive equivalent, the failure degree of prestressed steel reinforcement is aggravated, the number of anchorage falling off is increased, and the normal steel reinforcement evolved from failure to fracture. The fracture shape of the web of prestressed T-beam was “X”, and the failure form on both sides of the web was roughly “I” shape. The number of concrete cracks increased, and the crack depth and the size of the crack increased. The local failure mode of T-beam evolved from seismic collapse to penetrating failure, and the residual bearing capacity of prestressed T-beam gradually decreased.

Failure analysis on premature fracture of anchor bolts in seawater booster pump of nuclear power plant

Abstract Three of the four TP321 stainless steel anchor bolts used in an indoor seawater booster pump of a nuclear power plant were encountered with premature fracture during service. A comprehensive analysis was performed to investigate the operational conditions, base materials and macro/micro morphologies of the failed bolts to identify the failure causes. The results showed that a collection of banded inclusions was distributed among the grains by metallographic examination, and typical pitting holes were observed and high levels of chlorides were detected on the surfaces of the failed bolts' fractures by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). In addition, branched cracks were found on the axial sections of the fractured bolts. Given all that, the premature fracture of the anchor bolts was determined to be mainly caused by stress corrosion cracking (SCC) from chlorides, which was then proved to be induced by splashing of the seawater during routine maintenance of the pump. Besides, the sequence of fracture for these three anchor bolts was ascertained by fractography from three aspects, including shapes of fractures, morphologies of corrosion products and chemical compositions of corrosion products. Finally, countermeasures were put forward as well.

Tooth whitening affects bond strength of adhesive systems in enamel

This study presents how the tooth whitening affects the bond strength and fracture type of three distinct adhesives — a conventional, a self-etching, and a universal adhesive — in enamel. Health bovine incisors were prepared by flattening the labial surface; part of these teeth was submitted to whitening treatment with a peroxide-based product (WhiteGold Office© 35%). The Single Bond©, AdheSE©, or Single Bond Universal© adhesive system were used to adhere a block of restorative resin to the flat surface of the teeth. Sticks measuring 10x1x1 mm were prepared and used in microtensile tests; they were also employed to examine the type of fracture. The results are analyzed with a two-way ANOVA. For both whitened and non-whitened specimens, the adhesive systems did not give statistically different bond strength values. However, the fracture shape (classified into four types) varied from a cohesive enamel type fracture for the whitened samples to a predominantly cohesive resin type fracture for the non-whitened teeth. Therefore, the whitening procedure has exerted a weakening effect on enamel even after 21 days post-treatment. Keywords: Tooth whitening; adhesive systems; bond strength; fracture; restorative system.

Effect of Fluid Compressibility on Toughness-Dominated Hydraulic Fractures With Leakoff

Summary Hydraulic fracturing using supercritical carbon dioxide (CO2) has a recognized potential to grow in importance for unconventional oil and gas reservoirs. It is characterized by higher compressibility than traditional liquid-phase hydraulic-fracturing fluids. Motivated by the larger compressibility of supercritical CO2, this paper considers the problem of a hydraulic fracture in which a compressible fluid is injected at a constant rate to drive a hydraulic fracture in a permeable and brittle rock. The two cases of a plane-strain fracture and a penny-shaped fracture are considered. It is shown that for many practical cases, the formation has a large enough fracture toughness that the propagation is in a regime for which the pressure inside the hydraulic fracture can be treated as spatially uniform (“toughness dominated”). Both numerical simulations and analytical solutions for the relevant limiting regimes show that fluid compressibility affects fracture shape only at the very beginning period, which corresponds to the storage regime, and has little effect on fracture growth in the leakoff regime. Overall, because the transition from the storage regime to the leakoff regime is expected to often take place in a short time after the fracture starts propagating, the influence of compressibility in the storage regime is very brief and can be quickly ignored. Therefore, even relatively sizable fluid compressibility has almost no effect on fracture growth in the toughness-dominated regime when leakoff is taken into account.

Predictions of macro-scale fracture geometries from acoustic emission point cloud data in a hydraulic fracturing experiment

Observations of laboratory fracture testing by means of acoustic emission (AE) can provide a wealth of information regarding the fracturing process and the subsequent damage of the material or structure under load. A method for determining the structure of macro-scale fractures from a point cloud of AE events was developed and tested at the laboratory scale. An unconfined hydraulic fracturing experiment was performed on granite while monitoring acoustic emissions from six piezoelectric transducers on the surfaces of the specimen. The granite specimen dimensions were 30 × 30 × 25 cm3. The motivation of the AE analysis was to provide location information for a secondary wellbore placement which intersects the hydraulic fracture to complete a hydraulically connected binary well-hydraulic fracture system. Information gained from the 3D event source locations was used to optimize the location and orientation of secondary production well placement to intersect the induced hydraulic fracture. A direct method was developed to predict the location, orientation and shape of the hydraulic fracture from a dense cloud of AE events. The predicted fracture plane, which was assumed to be planar, was rotated in both the pitch and roll directions, while an average error of AE event distance between the assumed plane and the individual event locations was determined for each rotation iteration, resulting with a predicted fracture plane in the minimum error orientation. Post-test fracture observations were made and digitized in 3D space from coring and slabbing the granite specimen. The actual fracture observations were compared with the predicted fracture structure from AE and showed marked correlation. The simple method of determining macro-scale fracture location, orientation, and extents provided a useful tool for materials that exhibit large and disperse clouds of AE activity where coalesced fracture structure is not apparent.

Identification of brittle and ductile zones in sandstone reservoir using well log analysis; a case study, Southern Indus Basin, Pakistan

Brittleness and ductility play a very important role in the stimulation design of unconventional reservoirs as it controls the fracture length and shape of hydraulic fractures. The estimation of mechanical properties of the reservoir rock is very important for the successful execution of reservoir drilling, production, and development operations. In this study, the mechanical properties are calculated using well log responses for selected reservoir section after a quality check of the data. Brittleness is estimated from empirical correlations based on mechanical properties estimated from well logs response, uniaxial compression strength and tensile strength. High values of young modulus and corresponding low values of Poison’s ratio were indicating the brittle zones in the reservoir. Brittle-ductile zone identification based on mechanical properties were giving consistent results. Brittle-ductile categorization is done for identification of brittle, less brittle, less ductile and ductile reservoir lithology in each studied well. It was found from the computer-assisted approach and graphical presentation that, there was a high brittleness in the lower part of the reservoir which is due to highly compressed shale formation. This part of the reservoir could be a good candidate for hydraulic fracturing if it satisfies all other constraints for a prospective reservoir.

The workflow to analyze hydraulic fracture effect on hydraulic fractured horizontal well production in composite formation system

Hydraulic fracturing generally leads to highly complex hydraulic networks for tight oil reservoirs. It is significant to understand the hydraulic fracture effect on well performance. As an effective tool, semi-analytical solution for well pressure transient analysis (PTA) and rate transient analysis (RTA) is used in large amount because of higher calculation efficiency than numerical solution. In this paper, the PTA and RTA methods and result of composite formation system (CFS) are shown comprehensively. Firstly, a mathematical model of multistage fractured horizontal well (MsFHW) in CFS was proposed for tight oil reservoir with different regions and formation properties. In the model, two regions with different formation parameters were distinguished. This assumption of two regions, i.e. CFS is a composite tight reservoir formed after hydraulic fracturing. Difference of finite hydraulic fracture conductivity, inclined angle of hydraulic fracture, different shapes of multi-wing fractures in perforating point are considered to make this model powerful to analyze production performance of different MsFHW types. The inner and outer regions were assumed as dual porosity medium but single porosity medium model can also be solved by simplification. Then, the solution of MsFHW performance analysis model is obtained by source function method and the source function superposition principle which are common used in PTA and RTA. PTA for well producing at a constant production rate and RTA for well producing at a constant wellbore pressure were obtained and discussed. Different flow regimes were divided for different fracture geometry situations. The effects of different MsFHW types on PTA and RTA were analyzed. The inflow performance for different hydraulic fractures were presented. Cited as : Yuan, J., Jiang, R., Zhang, W. The workflow to analyze hydraulic fracture effect on hydraulic fractured horizontal well production in composite formation system. Advances in Geo-Energy Research, 2018, 2(3): 319-342, doi: 10.26804/ager.2018.03.09

Network Fracturing Techniques Research and its Application in Sandy Conglomerate Reservoir

The permeability of sandy conglomerate reservoir in Erlian Basin is low, and its heterogeneity is very strong, and that its connectivity is bad. The shape of hydraulic fracture in sandy conglomerate reservoir is not regular, and a lot of complicated fracture will be forming in the process of fracturing operation. The effect will not be good when applying common fracturing techniques. Aiming at the pay sand characteristic in BA101x reservoir of Baolige Oilfield, we use some technological means to evaluate brittle index and analyze stress profile; we establish fracture design method which suits sandy conglomerate of research area and develop low damage fracturing fluid which has energy storage function. The research achievement is apllyed in BA77-30x well, using fluid 2201m3 and proppant 112m3. The SRV is about 111×104m3. The well produces 258 day and the cumulative production is about 2393t(4.8 times comparing with common fracturing techniques). It is observed that the effect of network fracturing techniques is better than common techniques.