Influence Of Injection Rate Research Articles

A Semi-Analytical Model for Studying the Transient Flow Behavior of Nonuniform-Width Fractures in a Three-Dimensional Domain

In the fracture propagation model, the assumption that hydraulic fractures with non-uniform widths have been successfully utilized to predict fracture propagation for decades. However, when one conducts post-fracture analysis, the hydraulic fracture is commonly simplified with a uniform width, which is contradictory to the real fracture models. One of the reasons for over-simplifying the fracture geometry in the post-fracture analysis can be ascribed to the fact that we are still lacking a model to characterize the pressure transient behavior of the nonuniform-width fractures which can induce three-dimensional flow around the fractures. In this work, on the basis of the Green function and Newman product method, the authors derived a semi-analytical model to account for the effect of non-uniform width distribution of the hydraulic fractures in a three-dimensional domain. In addition, the effect of the fracturing strategies on the well performance is investigated based on the developed semi-analytical model. The calculated results from the developed model show that the vertical flow in the vicinity of the fracture cannot be neglected if the fracture height is sufficiently small (e.g., hf = 10 m), and one can observe vertical elliptical flow and vertical pseudo-radial flow during the production. A nonuniform-width fracture can penetrate further into the reservoir with a lower injection rate (e.g., qi = 1.44 × 103 md). For the scenarios of high fracture permeability (i.e., kf = 1 × 105 md), a smaller fracture height, lower injection rate, and larger Young’s modulus can be more favorable for enhancing the well productivity. Compared to the influence of fracture height, the influences of injection rate and Young’s modulus on the well performance are less pronounced.

Study on influence factors of saline aquifer CO2 sequestration under the constraint of cap rock

In view of the practical problems faced by the CO2 sequestration in aquifers, this paper considers the influence of injection rate, water production rate, and other factors on CO2 injection amount, residual sequestration amount, dissolution sequestration amount, and pressure evolution under the constraint of cap rock breakthrough pressure is studied by using a numerical simulation method, and the sequestration potential is evaluated. The results show that: (1) Water production measures can improve CO2 injection, dissolution sequestration, and residual sequestration. (2) Low ratio of vertical permeability to horizontal permeability is conducive to the security and stability of CO2 sequestration in the long term. The research content provides support for the evaluation of CO2 saline aquifer sequestration potential and field practice.

Influence of injection methods on calcareous sand cementation by EICP technique

Calcareous sands are widely distributed on continental shelves, coastal zones, islands and reefs in the tropical oceans. For being used as construction materials, calcareous sands should be artificially treated to improve their engineering properties. Enzymatically induced carbonate precipitation (EICP) is an innovative soil treatment technique. In this paper, urease was extracted from soybean powder using artificial seawater for calcareous sands cementing by the EICP technique. Cementation tests were conducted with three injection methods (the pre-mixed, staged and proposed parallel injections) and two injection rates (2 and 5 mL/min). The hydraulic conductivity, shear wave velocity (SWV) and unconfined compressive strength tests were conducted and the cementation effects were evaluated. The hydrodynamic diameter of the particles generated in the mixed solutions was measured with reaction time by a laser particle size analyzer and the influence of injection rate on the CaCO3 distribution in the specimen was discussed. The coefficient of variation of the SWV values along the cemented specimen height was calculated for evaluation of the cementation uniformity. Results show that a high injection rate was conducive to reducing clogging and improving the cementation uniformity by completing injection within the urea hydrolysis phase. The promising parallel injection method proposed in this study provided a lag time for reaction by simultaneous injection of crude urease and cementation solutions using two separate tubes. Specimens treated at a high parallel injection rate were uniformly cemented with high mechanical strengths and high overall hydraulic conductivities because of a high proportion of CaCO3 in contact-cementing distribution.

Influence of Injection Rate and Oil Viscosity on Viscous Fingering – Simulation Prediction

Waterflooding is a secondary oil recovery process that commonly utilized. However, there are several factors affecting the efficiency of water-flooding. Current research focused on the effects of injection rate and oil viscosity on the waterflooding efficiency. Fluid Structure Interaction (FSI) is utilized to predict the effect of the injection rate and oil viscosity towards waterflooding. Volume of fluid (VOF) and Realizable k- ɛ models are utilized in this research. Ergun’s equation also utilized in this research for estimation of permeability and inertial loss within the porous medium. The research found viscous fingering occurred when the mobility ratio is more than unity and instability number, Ni > 1000. The phenomenon of viscous fingering is directly affected by injection rate and viscosity ratio. The phenomenon directly affects directly sweep efficiency during waterflooding process thus affecting oil recovery process. The research found as injection rate and viscosity ratio increase; viscous fingering predominantly seen within the porous medium.

Rock Fracture Response Exposed to Hydraulic Fracturing: Insight into the Effect of Injection Rate on Aperture Pattern

Injection rate is critical to hydraulic fracturing operation, especially to the hydraulic fracture aperture, which affects the proppant and methane migration. In this study, hydraulic fracturing experiments were carried out on shale specimens to investigate the influence of injection rate on hydraulic fracture aperture. According to the experimental results, when the injection rate increases, the average aperture of hydraulic fracture shows a significant linear increase. For different injection rate, the average aperture of stimulated natural fracture is always slightly greater than that of newly opened fracture. Compared with a low injection rate, the fracture apertures induced by the largest injection rate are evenly distributed in more intervals and approximately conform to the normal distribution. The research results can provide a theoretical basis for enhancing the fracture conductivity of hydraulic fracturing in shale reservoirs.

Influence of Injection Rate on Mechanical Properties of the Molding Composition Based on Polyamide 6 and Carbon Nanotubes

This paper is devoted to obtaining and investigating polymer composites based on polyamide-6 and carbon nanotubes. Polyamide 6, type 210/310, was used as a polymer matrix, and carbon nanotubes manufactured by OcSiAl were used as a modifier. The components were compounded in a co-rotating twin-screw extruder HAAKE Rheomex OS PTW 16 to obtain granulate. The granulate was processed by injection molding on a Babyplast 6/10V machine to obtain test samples as double-sided blades (ISO-527-2, type 5A). Elastic strength tests were carried out on a Gotech UAI-7000M universal tensile-testing machine. It has been shown that introduction of 0.15% CNT promotes an increase in the yield point and the initial modulus of elasticity with a significant decrease in the ultimate strength. The maximum value of the tensile strength (161 MPa) has been obtained for the specified composition at an injection rate of 12.9 ml/s.

Study on the Adsorption of Hydrolyzed Polyacrylamide by Zeolitic Imidazole Framework

AbstractThree types of Zeolitic imidazolate framework‐8 (ZIF‐8 s), i. e. ZIF‐8(MeOH), ZIF‐8(H2O), and ZIF‐8(NH3.H2O), were synthesized by using different solvents. Influences of the ZIF‐8 type, hydrolyzed polyacrylamide (HPAM) property, and salinity of the solution on their adsorption performance were discussed. The results indicated that ZIF‐8(NH3 ⋅ H2O) showed larger adsorption capacity compared to other counterparts. An increase in the hydrolysis degree of HPAM had a positive influence on the adsorption capacity of ZIF‐8(NH3 ⋅ H2O). With the increase of NaCl concentration in the solution, the adsorption capacity of ZIF‐8(NH3 ⋅ H2O) first increased and then decreased. Adsorption thermodynamics and kinetic investigation showed that the adsorption of HPAM by ZIF‐8 is a spontaneous endothermic chemisorption process. The influences of injection rate, temperature, ZIF‐8 mass and HPAM initial concentration on the dynamic adsorption were investigated. The processing volume per unit mass of ZIF‐8 increased with the increasing temperature, ZIF‐8 mass and HPAM initial concentration, while decreased with the increasing injection rate. Lastly, the adsorption mechanism was analyzed. The results of IR and XPS confirmed that the HPAM adsorption on ZIF‐8 was caused by three interactions, including the electrostatic attraction between ZIF‐8 and HPAM, the coordination interaction between Zn2+ and NH+ with COO−, and the hydrogen bonding between nitrogen and amide group.

Numerical model for geothermal energy utilization from double pipe heat exchanger in abandoned oil wells

The number of abandonded wells are increasing in the late period of oilfield development. The utilization of these abandonded oil wells is promising and environment-friendly for geothermal development. In this study, a numerical model for geothermal heating is derived from a double pipe heat exchanger in abandoned oil wells. The main influencing factors of injection rate, injection time, and the types of filler in casing annulus on temperature profiles and outlet temperature have been considered in this model. The influences of injection rate on heat-mining rate are then discussed. Results show that the double pipe heat exchanger can gain higher temperature at the outlet when the casing annulus is filled by liquid other than dry cement under the given parameter combination. The outlet temperature decreases with the increase in injection rate and injection time. The temperature rapidly decreases in the first 40 days during the injection process. The balance between heat mining rate and outlet temperature is important for evaluating a double pipe heat exchanger in abandoned oil wells. This work may provide a useful tool for a field engineer to estimate the temperature of liquid in wellhead and evaluate the heat transfer efficiency for double pipe heat exchanger in abandoned oil wells. Cited as: Lin, Z., Liu, K., Liu, J., Geng, D., Ren, K., Zheng, Z. Numerical model for geothermal energy utilization from double pipe heat exchanger in abandoned oil wells. Advances in Geo-Energy Research, 2021, 5(2): 212-221, doi: 10.46690/ager.2021.02.10

Numerical Investigation on Hydraulic Fracturing of Extreme Limited Entry Perforating in Plug-and-Perforation Completion of Shale Oil Reservoir in Changqing Oilfield, China

In recent years, multi-stage hydraulic fracturing for shale oil reservoirs is developing toward a shorter cluster spacing and a larger number of clusters per stage. The objective is to improve the stimulation performance by reducing the fracturing stages and creating more hydraulic fractures in terms of cost-efficiency in geological engineering. Field tests demonstrate the uneven distribution of fluid volume among clusters and only a few perforation clusters contribute to productivity. The extreme limited entry (XLE) completion is an effective method to improve the efficiency of perforation clusters. However, the influence of several controlling parameters on the cluster effectiveness during XLE completion remains elusive. Therefore, a 3D field-scale hydraulic fracturing model for XLE completion based on the lattice method is developed for the case of shale oil reservoirs of Changqing oilfield in China. In this model, perforation friction, geological factor such as stress difference between adjacent clusters, and filtration of fracturing fluid are considered. The numerical results are compared with field data (i.e., injection pressure and cluster efficiency) obtained from the fracturing construction and the step-down test. The influences of injection rate, cluster spacing, cluster number, and stress difference between adjacent clusters on the fracture morphology, cluster efficiency and injection pressure of XLE completion are discussed in detail. The results show that perforation friction is the most critical factor that affects the efficiency of perforation cluster during XLE completion. A guide chart of cluster efficiency under various differential geological stresses between adjoining clusters is proposed. According to this guide chart, the required perforation friction under different cases can be obtained, and then the related perforation parameters (i.e., perforation diameter and number) can be determined. The research results provide theoretical guidance for optimization of XLE completion in geological reservoirs.

Influence of injection rate in determining the development of artifacts during the acquisition of dynamic arterial phase in Gd-EOB-DTPA MRI studies.

To assess whether different Gd-EOB-DTPA injection rates could influence the development of artifacts during the arterial phase of liver MRI studies. All Gd-EOB-DTPA liver MRI studies performed for different clinical indications at a single tertiary referral center were retrospectively evaluated. Each examination was acquired on a 1.5T scanner with T1 In- and Out-of-Phase, T2 with and without fat-saturation, DWI, and 3D-T1 fat-sat dynamic sequences. Patients were divided into two groups according to the injection rate (1ml/s and 1.5ml/s). A single radiologist recorded the presence or absence of artifacts during different acquisition phases, respectively: (1) all examination; (2) only during the arterial phase; (3) only during the portal-venous phase; (4) both in arterial and portal-venous phases. From a total of 748 MRI studies performed, 229 were excluded due to the presence of artifacts during the entire examination. The remaining 519 MRI studies were divided into two groups according to the injection rate. The first group (flow rate = 1ml/s) was composed by 312 (60.1%) patients and the second group (flow rate = 1.5ml/s) by 207 (39.9%) patients. In the first group, 2 (0.6%) patients showed artifacts in all dynamic sequences; 13 (4%) only in the arterial phase, 16 (5%) only in the portal-venous phase, and 38 (12%) both in arterial and portal-venous phases; a total of 243 (78%) showed no artifacts. In the second group, 3 (1.5%) patients had artifacts in all dynamic sequences, 82 (40%) only in the arterial phase, 20 (10%) only in the portal-venous phase, and 53 (25%) both in arterial and portal-venous phases; a total of 49 (23.5%) showed no artifacts. A significant difference between the two groups regarding the absence of artifacts in all examination and the presence of artifacts only during the arterial phase was found (p < 0.001). The development of artifacts during the arterial phase of Gd-EOB-DTPA liver MRI studies could be related to the injection rate and its reduction may help to decrease the incidence of artifacts.

Runaway inhibition of styrene polymerization: A simulation study by chaos divergence theory

We attempted to prevent the thermal risk of a runaway reaction of polymerization in a batch reactor and to realize online monitoring and emergency inhibition of the thermal runaway behavior. Styrene thermal initiation of bulk polymerization was studied. A full-size model of the styrene polymerization reactor was constructed by referring to the reactor model of the Mettler Toledo automatic calorimeter, which was combined with the kinetic and thermodynamic models of styrene polymerization. The DIV thermal runaway critical criterion based on chaos divergence theory was used to judge the thermal runaway reaction. The critical point of the runaway reaction was determined and used to inhibit the thermal runaway of styrene polymerization by injecting cooling diluents at the liquid surface. The influence of injection rate (vc=0.5、0.8、1m/s), injection position (in-1、in-2、in-3), and amount of cooling diluents (no add、50 %、70 %、100 %) injected on the thermal runaway inhibition of the reaction was investigated and elucidated. The results indicated that a better inhibiting effect can be obtained by injecting the inhibitors at higher rates near the edge of the paddle blade. Moreover, appropriately increasing the injection amount of the inhibitors can achieve better inhibition of the runaway reaction.

Numerical simulation of CO2 huff-and-puff process in a hydraulically fractured horizontal well in a tight oil reservoir

A numerical reservoir model was built using Computer Modeling Group's GEM simulator to study the process of carbon dioxide (CO2) huff-and-puff in the Bakken tight formation. The influences of injection rate, production time, and soaking time on the incremental oil recovery factor (IORF) were studied systematically, as was the utilization efficiency of CO2 during the whole production process. The results showed that higher injection rates are preferable to lower ones, and the huff-and-puff process works best with a soaking time of 0 days. The production time of each cycle could be optimized for a specific case to maximize IORF, and CO2 efficiency was found to decrease with increasing number of cycles. This study may shed light on how to optimize the CO2 huff-and-puff process and therefore achieve the best enhanced oil recovery performance.

Influence of injection rates of calibrating standard solution on monitoring pulse indicator continuous cardiac output

ObjectiveThis study aimed to investigate the influence of injection rates of calibrating standard solution on monitoring pulse indicator continuous cardiac output (PICCO, made in Germany), and thereby to provide significant references for clinical practice.MethodsA total of 108 critical patients in stroke intensive care unit were identified. All these participants received transesophageal cardiac color Doppler ultrasound, and within 15 min PICCO equipment was utilized to monitor the relevant parameters, by means of 0 °C calibrating standard solution, and the injection speeds were 2–4, 5–7, and 8–10 s. Besides, the monitoring indicators were as follows, cardiac index, global ejection fraction, global end diastolic volume index. The potential correlations were evaluated between PICCO and transesophageal cardiac color Doppler ultrasound.ResultsAll the data was available, and the monitored parameters of PICOO at 2–4, 5–7, and 8–10 s were positively correlated with the parameters obtained from transesophageal cardiac color Doppler ultrasound (P < 0.05). Specially, it is worth emphasizing that the best correlation between them could be provided when the injection rate was 2–4 s.ConclusionWhen the injection rate at 2–4 s, the parameters obtained by PICOO were much closer to that of transesophageal cardiac color Doppler ultrasound. Furthermore, the parameters of PICOO obtained at 2–4 s could better reflect cardiac function of patients.

CO2−DSAの画質に対する注入速度と水流の影響について ファントムによる研究

CO2−DSAの画質に対する注入速度と水流の影響について ファントムによる研究

Numerical simulation of simultaneous multiple fractures initiation in unconventional reservoirs through injection control of horizontal well

Simultaneous fracturing stimulations in horizontal well are effective tools for promoting productivity of unconventional reservoirs. However, fracture lengths and widths of some perforation clusters may be restricted due to the stress shadow effects. In this paper, a numerical model to simulate nonplanar fractures simultaneous initiation in porous media is established based on the extended finite element method (XFEM). The amount of fluid flowing into each fracture is dynamically calculated with a total injection volume in this model. Sensitivity studies of formation parameters on fractures geometry of simultaneous fracturing are presented. The in-situ stress contrast is found to be the main factor controlling the fractures propagation. The initiation of interior fracture will be restricted or compressed to be closed in the vicinity of the injection point. The influence of injection rate and perforation friction on fractures initiation is investigated. Strategies to optimize fractures geometry are presented through injection control of each fracture. The method presented in this paper can be used in horizontal well design to achieve reasonable fractures geometry.

An investigation of the acoustic emission generated during crystallization process of salicylic acid

Due to its non-invasive and non-destructive nature, Acoustic Emission (AE) has been successfully used in a wide variety of solids elaboration process. But few papers reported that solution crystallization process give rise to acoustic emission signals that could be related to the basic crystallization phenomena. This study is intended to evaluate the potential for using acoustic emission to monitor the physicochemical crystallization process. The potential relationship between the generation of acoustic signals and the physicochemical crystallization process of salicylic acid (SA) is analyzed by intensity of AE signal and pH value of the solution. Due to its great impact on end-product quality, SA crystal particles are investigated under the influence of injection rates. The results demonstrate that the mode of the particle size distribution is inversely related to the injection rates. In addition, the intensity of AE is obviously influenced by the injection rates. Moreover, the changing tendencies of AE are related to the basic crystallization phenomena, and the intensity of AE can be an important technical parameter to characterize the physicochemical crystallization process. The valuable AE information could increase process understanding and provide a basis for innovative online monitoring and control application.

Influence of injection rate on crystallization of injection-molded β-nucleated isotactic polypropylene

It is widely believed that β-nucleating agent is beneficial for effectively toughening isotactic polypropylene (iPP). However, for the injection molding process, the shearing and thermo-mechanical conditions make the nucleation and crystallization process complicated. In this paper, the effects of injection rate on crystallization of β-nucleated iPP were studied by scanning electron microscope (SEM), two-dimensional wide-angle X-ray diffraction and differential scanning calorimetry (DSC). It is observed that with increasing injection rate, the content of β-crystals exhibits different tendencies in the skin, intermediate layers, and core zone. Specifically, for the intermediate layer, the β-crystals content first increases with increasing injection rate to 85 cm·s−1, and begins to decrease afterward. By simulating the injection process, the most likely explanation for the β-crystal change is the comparatively high shear rate and low shearing time that the melt experienced. Variations in β-form content are mainly responsible for the mechanical properties of β-nucleated iPP. The results of this study provide a valuable way to control the iPP toughness in the injection molding process. POLYM. ENG. SCI., 57:172–182, 2017. © 2016 Society of Plastics Engineers

Numerical simulation of preformed particle gel flooding for enhancing oil recovery

Abstract As a new type of oil recovery enhancing technology, preformed particle gel (PPG) flooding has been gradually used for high water-cut reservoir development. However, the current commercial software cannot simulate the processes of PPG flooding. In this paper, a novel mathematical model considering the behaviors of pore-throat plugging and particles restarting, the matching relations of particle size, throat size and pressure gradient is established based on the mass conservation equation and solved by IMPES and typical four-order Runge–Kutta methods. Also, the codes are written by Visual Basic, and the verification is proved by experimental data. Then, the influences of injection rate, suspension concentration, mean particle diameter, critical threshold pressure gradient and permeability ratio in ultimate oil recovery factor and water-cut are studied. The results show that, with the injection rate, mean particle diameter and critical restarting pressure gradient coefficient increasing, the ultimate oil recovery factor will increase first, and then decrease. As the concentration of injection suspension increases, the ultimate oil recovery factor will increase first, but at the later stage it tends to be smooth. As the permeability ratio increases, the enhanced recovery factor will also increase first, and then tend to be smooth.

Thoracic and abdominal MRA with gadofosveset: Influence of injection rate on vessel signal and image quality

The purpose of this study was to investigate the influence of different injection rates on the maximum signal intensity and the arterio-venous transit time of dynamic gadofosveset-enhanced first pass MR angiography (MRA). Twenty-one healthy male volunteers were examined with a time-resolved echo-shared MRA at 1.5 T. The volunteers were assigned into three groups using injection rates of either 1, 2 or 4 ml/s. The maximal signal enhancement and peak signal-to-noise ratio in the pulmonary trunk, the aortic arch, the abdominal aorta as well as both kidneys and lung parenchyma were analyzed. The arterio-venous transit time was determined. The time between maximal enhancement of the pulmonary trunk and the aortic arch was higher with the slow injection rate of 1 ml/s, while there were no differences in the time between maximal enhancement of the aortic arch and the abdominal aorta above or below the origin of the renal veins with all three injection rates. With the slow injection protocol of 1 ml/s a longer purely arterial phase of 10.5 s was achieved compared to 7.7 s with higher injection rates (p = 0.045). The time between maximal aortic signal intensity and maximal renal enhancement was equal for all injection protocols.

Influence of Injection Rate of Hyperbaric Bupivacaine on Spinal Block in Parturients: A Randomized Trial

Influence of Injection Rate of Hyperbaric Bupivacaine on Spinal Block in Parturients: A Randomized Trial