Injection Profile Research Articles

MODELING OF WATER-ISOLATING SYSTEM GEL TIME FOR OIL WELLS

Currently, a high water cut in wells is one of the main problems of the oil industry. Its presence leads to a decrease in the flow rate of wells, an increase in the volume of work connected with the dewatering and trans- portation of products, an increase in the number of annular flows in wells, the destruction of bottom-hole formation rocks and the formation of sand plugs. One of the available and effective ways to solve this prob- lem is the use of methods for limiting water inflow, and in particular, technologies for leveling the injectivity profile in injection wells. During these works fulfilling, an important characteristic is water isolat- ing system gel time, which is affected by various parameters. This is the time required for the gel to transition from a free fluid into a solid or semi-solid, after which its transfer becomes difficult. In this work, an organically crosslinked system containing an acrylate copolymer crosslinked with a polyamine was chosen as a water insulat- ing material. Different formulations were developed using 2 % and 5 % potassium chloride (KCl), used as an acidic agent. The gel time of vari- ous compositions was determined at temperatures of 60 °C and 88 °C. According to the research results, the corresponding dependencies were established. To quantify the degree of influence of these parameters on the gel time, factor analysis was performed, which showed that the temperature parameter had the greatest effect. Also based on the results of the research, a mathematical model was developed for predicting the gel time, which describes the mechanism by which the three parameters considered are affected: the concentration of the crosslinker, the concen- tration of the acidic agent, and temperature.

Prediction of pressure and temperature changes in the salt caverns of Tuz Golu underground natural gas storage site while withdrawing or injecting natural gas by numerical simulations

Tuz Golu (Salt Lake) Underground Gas Storage (UGS) Project in Turkey is being implemented. In some of salt caverns, natural gas is currently stored. While analyzing the data of Tuz Golu UGS project, it was observed that this location is appropriate for safe underground natural gas storage due to its rock salt with high purity and very low permeability. In this study, many numerical simulations for a salt cavern in Tuz Golu UGS project at different gas withdrawal and injection rates were conducted by using TOUGH + RealGasBrine simulator. According to the results of these numerical simulations, the temperature inside salt cavern reduced below 0 °C from 53 °C within 20 days at a rate of gas withdrawal of 3.33 million standard m3/day due to Joule-Thomson effect. The temperature inside salt cavern reduced below 0 °C within 25 days, 40 days, and 60 days at a rate of gas withdrawal of 2.5, 1.67, and 0.833 million standard m3, respectively. In order to avoid fracture around the walls of salt cavern, the temperature change inside salt cavern should not be higher than 30 °C. In the numerical simulations, there is no gas seepages from the salt cavern to other neighbor salt caverns, which are 600 m away owing to very low permeability of salt rock in the study area. The implication of this study is that gas withdrawal and gas injection profiles are quite important to keep the temperature inside salt caverns at an optimum range for safe natural gas storage.

Injection profile inversion timing judgment model for polymer flooding and its theoretical validation

In the background of low oil price, polymer flooding plays a crucial role in offshore development of high-permeability and viscous oil reservoirs. However, during the whole flooding process, profile inversion occurred frequently and could lead to inefficient or low efficient circulation of polymer. Knowing the timing of profile inversion could implement the multi-plug mobility adjustment technology duly, it can effectively expand the sweep volume. At present, the mechanical control factors and influence laws of the profile inversion timing are still unclear, and the suitable mathematical model for judging the timing of profile inversion is also missing. Therefore, on basis of two-layer one dimensional flow model of heterogeneous reservoir, the flow rate distribution model and profile inversion timing judging model are established respectively. These two models are verified by fitting changing parameters of resistance factor using polymer core flooding data, and the influence rules of polymer profile inversion timing are also discussed in this paper. The results show that profile inversion timing is affected by parameters c and d on high permeable layer and parameter b on low permeable layer, which parameters b and d have negative correlation and parameter c has positive correlation with the timing. Based on the established profile inversion timing judgment model and combined with polymer core flooding relative flow ratio data, we can obtain the changing parameter of resistance factor which provide a new quantitative method to evaluate polymer system, predict flooding effect and judge implement time of multi-plug injection technology.

Robust Optimal Control-based Design of Combined Chemo- and Immunotherapy Delivery Profiles

This paper addresses the problem of drug injection schedules design for cancer treatment, in the presence of model parametric uncertainties. It is commonly known that achieving optimal recovery performances under uncertainties is a complex task. Therefore, we propose to use a recent optimal control approach, based on the moment optimization framework. This method allows to formulate and solve robust optimal control problems by taking into account uncertain parameters and initial states, modeled as probability distributions. We analyse a two dimensional model that describes the interaction dynamics between tumor and immune cells. Furthermore, we derive statistically optimal combined strategies of chemo-and immunotherapy treatments, assuming the knowledge of probability distributions of some uncertain model parameters, namely, the tumor growth rate and the rate of immune cells influx. Numerical simulations are carried out in order to illustrate the effects of parametric uncertainties on dynamics, when using a nominal injection profile. Finally, we compare the recovery performance of nominal and robust schedules.

Analysing the efficiency of flooding oil reservoirs with water-soluble polyacrylamide and preliminary cross-linked polyacrylamide particles

Due to the constant increase in the number of fields entering the final stage of operation, oil companies are increasing their demand for integrated technologies that can simultaneously increase the coverage of the formation by the displacement process and reduce the water cut of well products. In this case, the traditional technology is flooding with viscous solutions of water-soluble polyacrylamide. The article provides an overview of polymer flooding technology, identifies the advantages and disadvantages of this approach, in particular, lists the factors that can influence the rheology of a polymer solution. Despite the widespread use of flooding based on polyacrylamide gels, this method has several limitations, which are primarily associated with the rheological characteristics of the polymer. The instability of the rheological characteristics of the polymer is a significant drawback, which can cause the unattainability of the desired oil recovery coefficient (CIN). An alternative for alignment of the injectivity profile is the technology of water flooding of the CHPG (polymer gel particles - preformed particle gels) based on a suspension of crosslinked polyacrylamide particles. The synthesis of such a polymer is carried out in advance and involves the formation of a three-dimensional structure (3D polymer). Based on the performed literature review, a comparative analysis of the effectiveness of technologies based on water-soluble polyacrylamide and pre-crosslinked polyacrylamide particles is given, as a result, it is concluded that the latter are advantageous in a number of significant indicators. Polymers based on CHP do not change the rheological characteristics during the injection process, while the particles can change shape and tear, enveloping obstacles. In addition, the technology allows you to start the injection of a suspension with a smaller volume of reagent, sequentially selecting the optimal particle size distribution depending on the specific geological and technological conditions of the formation. NPG-based flooding has high prospects for implementation in Russian oil fields.

A fracture identification method for low-permeability sandstone based on R/S analysis and the finite difference method: A case study from the Chang 6 reservoir in Huaqing oilfield, Ordos Basin

Low-permeability reservoirs are characterized by poor physical properties, strong heterogeneity and natural fractures. Accurate identification of the fracture distribution is of great significance for the exploration and development of low-permeability reservoirs. Field outcrop, core and imaging log analyses show that stratabound vertical and high-angle structural fractures are the main types of fractures in the Chang 6 formation in the Huaqing oilfield. The fracture orientations include NE-SW, NNE-SSW, NW-SE, and NNW-SSE. The NE-SE-oriented fractures formed in the Himalayan stage, while the NW-SE fractures formed in the Yanshan period, and the other fractures derived from the fracturing in the Yanshan period during the Himalayan tectonic activity. The traditional rescaled range (R/S) analysis method is upgraded by introducing the finite difference (FD) method in this research, and the newly proposed method is called the R/S-FD method. Core data show that the R/S-FD method can accurately recognize vertical fractures and high-angle fractures. By comparing the fracture development section on the imaging log, it is found that fractures discrimination parameter F has a good linear relationship with both the fracture linear density and the fracture surface density. This method is verified by dynamic data (water injection profiles) and static data (image logging), and the results show that the recognition error is eliminated when the lower limit of F is 0.5, resulting in a crack identification accuracy of 76.9%. Combining the R/S and finite difference methods reduces the artificial recognition error of the traditional R/S method, and the recognition process is automated and intelligent. The R/S-FD method can be used in combination with multiple logging curves. A high fracture recognition accuracy could be accomplished by using this proposed method with only conventional logging curves, of great practical significance to some low-permeability oilfields that lack image logging data.

Technical Application of Petroleum Logging Instruments in Marine Logging

Abstract To solve the problem of offshore oilfield development, based on the newly introduced pulsed neutron oxygen activation logging instrument, the application research of test design and interpretation method was carried out and applied to actual production. The structure, technical indicators and logging principles of pulsed neutron oxygen activation logging tools were introduced. The test design under different well conditions was studied, including general positive and negative injection, oil sleeve injection, single oil pipe configuration and multitubing configuration. A large amount of field test data was collected and analysed technically. A set of effective interpretation models was proposed. The corresponding interpretation software was developed. A set of test design methods and operating specifications for different well conditions were developed. Based on the conventional interpretation method, the peak selection, the double-tuber peak identification and the carbon dioxide flooding interpretation method were added. The results show that the test design and interpretation methods were applied well through a large number of field tests and production applications. Therefore, pulsed neutron oxygen activated injection profile logging technology is successfully applied in offshore oil fields.

Numerical simulation of reservoir stimulation with reference to the Newberry EGS

Heat production from an enhanced geothermal system (EGS) requires a successful stimulation. Cold water is injected into hot rocks to enhance the heat reservoir permeability. During injection, pore pressure, temperature and the stress field in the reservoir change significantly. Most hot dry rock masses are to some extent naturally fractured at various scales. Fractures could dilate and slip in shear possibly and propagate as a result of stress changes, increasing reservoir permeability. The objective of this work is to analyze the response of a naturally fractured heat reservoir to water injection. A fully coupled thermo-poroelastic finite element model is developed and used to describe the interaction between fluid flow, rock deformation, and heat transfer within the fractured rock. A fracture network model is generated based on field data and implemented into the coupled model. The model is used to simulate and analyze reservoir stimulation in the Newberry EGS Demonstration. In particular, the Phase 2.2 stimulation is modeled using field data on the fracture network, in-situ stress and laboratory data on rock and fracture properties. The simulated injection profile, the evolution of permeability and induced micro-seismic events agree with field observations. Simulation results also show that injection induced stress state changes occur around the injection well explaining the noted differences between the stress regimes obtained prior and subsequent to stimulation.

Phenomenological modeling of diesel spray with varying injection profile

Accurate and quick prediction of spray characteristics such as spray penetration is paramount for the understanding and quantitative analysis of the combustion process in diesel engines, in order to perform parametric study on advanced combustion process in diesel engines, zero-dimensional diesel spray model is often used for the prediction of the spray evolution. In this study, a previous zero-dimensional diesel spray model applied for the spray penetration prediction including the part after the end of injection with a constant injection rate was extended to the cases with varying injection rate. The effective injection velocity was introduced into the previous spray model, which is defined as the ratio of the momentum flux and fuel mass flow rate over the spray tip cross-sectional area. Combined with this definition, the analysis of effective injection rate and its response time was performed during and after the end of injection. After that, the fuel mass flow rate and momentum flux over the spray tip cross-sectional area were derived for varying injection rate even after the end of injection based on the momentum and fuel mass conservation along the spray axis, and further the spray penetration. Finally, the developed model was validated by comparing with the experimental data.

Systematic Design of Multivariable Fuel Injection Controllers for Advanced Diesel Combustion

With multiple fuel injections per combustion cycle, the advanced diesel combustion process depends on all injection pulses in a coupled way. This makes the control of the multipulse fuel injection profile challenging, and the currently employed decoupled design methods might fail to guarantee closed-loop stability. Without explicit consideration of disturbances, it is also difficult for current design methods to guarantee the robustness of a fuel injection controller. In this paper, we present a general framework that describes the cycle-to-cycle fuel injection control problem. A control-oriented model is introduced and locally validated with experimental data. It considers the disturbances and captures the coupled relation between the multipulse fuel injection profile and the combustion process. Based on the general framework and the control-oriented combustion model, we propose a systematic design approach to synthesize a multivariable fuel injection controller. With guaranteed robust stability and fast settling time (0.5 seconds/5 combustion cycles in experiments), the controller’s reference tracking performance and disturbance rejection capability are demonstrated experimentally on a single-cylinder engine test bench.

Prediction of wall impingement in a direct injection spark ignition engine by analyzing spray images for high-pressure injection up to 50 MPa

This study was performed to analyze the wall impingement and fuel film formation in a DISI engine with injection strategies using image-based analysis and CFD. The direct injection engine uses a high-pressure injection strategy to improve the homogeneity of the air-fuel mixture, so the spray behavior was analyzed by spray visualization for various injection pressures, and the wall impingement was predicted for various engine operating conditions based on the acquired images. The mass distribution of the injected fuel was calculated using the injection profiles and the spray image, and the amount of fuel that impinges on the piston and wall (i.e., the geometric boundaries of the cylinder) was calculated using data from the spray behavior for various engine operation conditions such as load and engine speed. The image-based analysis was limited to understanding the influence of the injection strategy on the droplet behavior after wall impingement of the fuel spray. Therefore, CFD using KIVA 3 V code was additionally conducted to analyze the effects of the injection strategies on wall film formation and droplet rebounding reflecting in-cylinder conditions. In the early- and late-injection conditions, the initial piston position is high, and most of the injected fuel impinges on the piston. As the injection pressure increases, the injection timing at which wall impingement occurs is advanced because of the rapid spray development. The results of the 3D analysis for the temperature and the intake flow in the engine cylinder showed that both the wall impingement and the fuel film were reduced as the injection pressure increased because the fuel evaporation increased due to improved atomization.

Simulation of a Distributed Cathode in a Linear-Format Crossed-Field Amplifier

The effects of a distributed cathode in a linear-format crossed-field amplifier are simulated in VSim and analyzed. A linear-format, injected-beam, 150-MHz, low-power (~100 W), moderate-gain (7 dB), meander-line crossed-field amplifier (CFA) designed and tested at Northeastern University is used as the basis for the simulation model. The simulation results were validated by the experimental results from that CFA. The injected-beam model was then replaced with a distributed cathode requiring electron injection with an energy below the sole electrode. A new method, which uses a divergence-free region, was developed to simulate this distributed cathode. This model was validated and studied using three different current injection profiles. The distributed cathode offered no improvements to gain or the signal-to-noise ratio (SNR). Increasing the cathode area lowers the noise but is counteracted by the corresponding decrease in gain. The limits to the gain in this particular device are due to the current space charge limit for the higher power operation and the SNR for the lower power operation.

Design-oriented regression models for H2O2 decontamination processes in sterile drug product manufacturing considering rapidity and sterility

We developed regression models for designing rapid and effective H2O2 decontamination processes in the manufacturing of sterile drug products such as injectables. Decontamination, which is typically performed by using H2O2, is a critical changeover process used to establish a sterile environment for filling products. In the process, there is a trade-off relationship between the duration of the process and the level of sterility assurance that needs to be considered in the design. Our model defines these two items as objective functions and the parameters describing the profile of H2O2 injection and the initial humidity as design variables. Our model also considers aeration, i.e., removal of H2O2 from the environment, as a part of the entire process. This design-oriented modeling considering the entire process is the novelty of the work. Experiments were performed using an industrial isolator to develop and validate a set of regression models that describe the relationship between the design variables and the objective functions. In the application of the model, Pareto-optimal conditions could be indicated given the target H2O2 concentration in aeration, which is useful for the makers of drugs and/or isolators for designing decontamination processes.

Consistent tracer administration profile improves test–retest repeatability of myocardial blood flow quantification with 82Rb dynamic PET imaging

ObjectivesQuantification of myocardial blood flow (MBF) and stress/rest flow reserve is used increasingly to diagnose multi-vessel coronary artery disease and micro-vascular disease with PET imaging. However, variability in the measurements may limit physician confidence to direct revascularization therapies based on specific threshold values. This study evaluated the effects of rubidium-82 (82Rb) tracer injection profile using a constant-activity-rate (CA) vs a constant-flow-rate (CF) infusion to improve test–retest repeatability of MBF measurements. Method22 participants underwent single-session 82Rb dynamic PET imaging during rest and dipyridamole stress using one of 2 test–retest infusion protocols: CA–CA (n = 12) or CA–CF (n = 10). MBF was quantified using a single-tissue-compartment model (1TCM) and a simplified retention model (SRM). Non-parametric test–retest repeatability coefficients (RPCnp) were compared between groups. Myocardium-to-blood contrast and signal-to-noise ratios of the late uptake images (2 to 6 minutes) were also compared to evaluate standard myocardial perfusion image (MPI) quality. ResultsMBF values in the CA–CA group were more repeatable (smaller RPCnp) than the CA–CF group using the 1TCM at rest alone, rest and stress combined, and stress/rest reserve (21% vs 36%, 16% vs 19%, and 20% vs 27%, P < 0.05, respectively), and using the SRM at Rest and Stress alone, Rest and Stress combined, and stress/rest reserve (21% vs 38%, 15% vs 25%, 22% vs 38%, and 23% vs 49%, P < 0.05, respectively). In terms of image quality, myocardium-to-blood contrast and signal-to-noise ratios were not significantly different between groups. ConclusionsConstant-activity-rate ‘square-wave’ infusion of 82Rb produces more repeatable tracer injection profiles and decreases the test–retest variability of MBF measurements, when compared to a constant-flow-rate ‘bolus’ administration of 82Rb, especially with SRM, and without compromising standard MPI quality.

Spasticity management with botulinum toxin: A comparison of UK physiotherapy and rehabilitation medicine injectors

Background/Aims: To compare patient outcomes following botulinum toxin (BoNT) injection by either physiotherapy or rehabilitation medicine (medical) professionals over a 3-year period. Methods: A retrospective, observational cohort study was conducted in a specialised rehabilitation service providing spasticity management including BoNT injection and physical therapy (group therapy, individual therapy, self-exercise, and physical management programmes). Individualised goals were established before treatment using goal attainment scaling (GAS) by the multidisciplinary team. The Arm Activity measure (ArmA) was used to evaluate upper limb function and the Modified Ashworth Scale (MAS) used to evaluate spasticity. Findings: A total of 262 patients were injected. Mean GAS T-score after treatment for the group was 50.2 ± 6.7. GAS T-score for physiotherapy injectors (n=214 (82% of participants)) was 50.2 ± 6.4 and for rehabilitation medicine injectors (n=48 (18%)) 50.3 ± 7.9. No significant differences were identified in terms of goal achievement, upper limb passive function, or spasticity reduction between physiotherapy and rehabilitation medicine injectors. Differences were identified at both baseline (physiotherapist mean 49.7; rehabilitation medicine mean 46.6) and follow-up for active function (physiotherapist mean=49.7; rehabilitation medicine mean=47.8) (ArmA active function subscale; p=0.03). No reportable adverse effects were recorded. No difference in the complexity of injection (such as complex clinical presentation, anticoagulation, or technical difficulty) between the injector groups was identified. Conclusions: Clinical outcomes were comparable between physiotherapy and rehabilitation medicine injectors. No difference in side effect profile or complexity of injection was identified. In this cohort, injection of BoNT by a physiotherapist was as effective in terms of GAS as that undertaken by a rehabilitation medicine physician.

Fluid flow characteristics during polymer flooding

At present the main problems of polymer flooding is the high injection pressure which could not guarantee the later injection. In this paper the analyses of polymer’s physical properties and its solution’s variable movement characteristics in porous media reveal the inevitable trend of decrease in injection capacity and liquid production due to the increase of fluid viscosity and flow rate with more flow resistance. The injection rate makes the primary contribution to the active viscosity of the polymer solution in porous media. The higher injection rate, the greater shearing degradation and the more the viscosity loss. Besides the quantitative variation, the rate also changes qualitatively as that the injection rate demonstrates composite change of injection intensity and density. Due to the different adjustment function of the polymer solution on its injection profile, there should be different adjustment model of rates in such stages. Here in combination of the on-site recognitions, several conclusions and recommendations are made based on the study of the injection pattern adjustment during polymer flooding to improve the pressure distribution system, which would be a meaningful reference for extensive polymer flooding in the petroleum industry.

Complications and Safety Profile of Posterior SubTenon Injection of Triamcinolone Acetonide

Purpose: Posterior Sub-Tenon injection (PSTI) is a common route of drug delivery for triamcinolone acetonide (TA) for intraocular inflammation. The aim of this study was to evaluate indications, complications and safety of PSTI of TA for intraocular inflammation. Method: This is a retrospective study. The duration of study was from October 2007 to December 2016. The patients with minimum 1 year after PSTI of TA follow-up were included in the study. All complications of injection procedure and drug itself were included. Patients with pre-existing lenticular opacity, glaucoma, blepharoptosis, traumatic macular edema, subconjunctival hemorrhage, traumatic uveitis, postoperative uveitis, and retinal vascular occlusive disorder were excluded from the study. Results: A total of 112 eyes of 110 patients who were treated with PSTI of TA were included in the study group. The mean age was 50±8.4 years. Out of 110 patients, 80 (72.72%) were females and 30 (27.27%) males. The recurrent anterior uveitis was the most common indication (44.64%). Out of 112 eyes, 100 eyes (89.28%) were injected once, 10 eyes (8.92%) twice, and 2 eyes (1.78%) thrice. Following PSTI of TA, 14 eyes (12.5%) developed ocular hypertension 6 eyes (5.35%) ptosis, and 3 eyes (2.67%) cataract. Conclusion: PSTI of TA has higher risk of steroid-induced glaucoma; hence these patients should be monitored for intraocular pressure.

Efficacy and Safety Profile of Risperidone Long-acting Injection in Adolescents in a Real-life Setting.

ObjectiveRisperidone long-acting injection (RLAI) was shown to be an alternative option in adult patients, but there is not available data in child and adolescents about this medication. The aim of this study is to evaluate the safety and efficiency profile of RLAI in a group of adolescents.MethodsEleven cases with conduct disorder and severe aggressive behaviors were initiated treatment with risperidone oral form. All cases were then shifted to RLAI 25 mg injection in each 15 days due to poor compliance to oral risperidone treatment. Efficiency of treatment included indicators of clinical severity and improvement, which were evaluated by Clinical Global Impression-Severity (CGI-S) and Improvement (CGI-I). Safety evaluation was performed by using Extrapyramidal Symptoms Rating Scale, and by monitoring body weight. Follow-up visits were done at the treatment initiation, and 8th, 16th, and 24th weeks of first injection.ResultsStudy included 9 girls, and 2 boys, with a mean age of 14.9±1.0 years. The CGI-S scores decreased from 6.6±0.5 at the beginning to 2.2±1.1 at the last visit (p<0.001), which is a very significant decrease through better clinical level. The CGI-I scores were also improved significantly from 2.4±0.5 to 1.9±0.5 at 24th week (p=0.001). Safety parameters were also showed favorable results, which there was no significant weight gain (p=0.076), and well-tolerated extrapyramidal adverse effects.ConclusionOur results showed that RLAI is an efficient and safe medication option in the treatment of psychiatric disorders and severe behavioral problems in adolescents with low-compliance to oral treatment in our cases.

Computational methodology for non-evaporating spray in quiescent chamber using Large Eddy Simulation

Large Eddy Simulation of a single non-evaporating spray in a quiescent chamber is carried out in this paper. The spray is injected with a given angle, velocity and drop size in a quiescent chamber with ambient conditions. Initially, a detailed sensibility analysis of various injection velocity profiles and subgrid carrier phase models, in the absence of droplet breakup and collision models, is carried out to capture the detailed turbulent flow features. The resulting spray behaviour is compared to mono-phase jet characteristics. The results provide basis for the selection of suitable turbulence model and injection profiles of the droplets for performing spray simulation in quiescent environmental conditions. Lastly the spray simulations are performed under realistic engine like conditions. For this purpose appropriate turbulence and droplet injection models along with droplet breakup model and collision model are used. The results are compared with the experimental data. The droplet size and fluctuating velocities are found to match reasonably well with experimental data.

Effects of carrier injection profile on low noise thin Al0.85Ga0.15As0.56Sb0.44 avalanche photodiodes.

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