Optimization of the Algorithm for Increasing Injection Rate in Water Injection Wells for Pressure Optimization in P Oilfield

In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy security. In order to improve the quality of water injection in the oilfield and gradually achieve efficient and stable production, Bohai Oilfield has launched a water injection well pressure optimization project, focusing on improving the efficiency and quality of water injection in the water injection wells, in order to achieve the optimal water injection plan. In practical work, P Oilfield continues to promote the development of water injection well pressure optimization projects, emphasizing practical exploration and continuous optimization of work plans. However, during the project implementation process, there were some problems, one of which was that the statistics of cumulative injection volume were not scientific enough, resulting in a more comprehensive and accurate presentation of the actual results of pressure optimization work. In the context of continuous improvement work, after careful analysis and research, P Oilfield has decided to optimize the cumulative injection rate algorithm to guide the oilfield’s water injection work in a more refined way, ensuring sufficient and good water injection, and enhancing the oilfield’s production efficiency and comprehensive competitiveness.

Development and prospect of downhole monitoring and data transmission technology for separated zone water injection

This article outlines the development of downhole monitoring and data transmission technology for separated zone water injection in China.According to the development stages,the principles,operation processes,adaptability and application status of traditional downhole data acquisition method,cable communications and testing technology,cable-controlled downhole parameter real-time monitoring communication method and downhole wireless communication technology are introduced in detail.Problems and challenges of existing technologies in downhole monitoring and data transmission technology are pointed out.According to the production requirement,the future development direction of the downhole monitoring and data transmission technology for separated zone water injection is proposed.For the large number of wells adopting cable measuring and adjustment technology,the key is to realize the digitalization of downhole plug.For the key monitoring wells,cable-controlled communication technology needs to be improved,and downhole monitoring and data transmission technology based on composite coiled tubing needs to be developed to make the operation more convenient and reliable.For large-scale application in oil fields,downhole wireless communication technology should be developed to realize automation of measurement and adjustment.In line with ground mobile communication network,a digital communication network covering the control center,water distribution station and oil reservoir should be built quickly to provide technical support for the digitization of reservoir development.

Horizontal Well Interference Performance and Water Injection Huff and Puff Effect on Well Groups with Complex Fracture Networks:A Numerical Study

Well interference has become a common phenomenon with the increasing scale of horizontal well fracturing.Recent studies on well interference in horizontal wells do not properly reflect the physical model of the postfracturing well groups and the realistic fracturing process of infill wells.Establishing the correspondence between well interference causative factors and manifestations is of great significance for infill well deployment and secondary oil recovery.In this work,we develop a numerical model that considers low velocity non-Darcy seepage inshale reservoirs to study the inter-well interferencephenomenon that occurs in theSantanghufield,andconstruct an explicit hydraulic fracture and complex natural fracture network model with an embedded discrete fracture model,focusing on the effect of fracture network morphology on well interactions.The model also considers a multi-segment wellbore model to accommodate the effect of inter-well crossflow on wellbore tubular flow.The changes in formation pressure and water saturation during fracturing are performed by controlling the injection pressure and water injection rate.The result shows that the shape of the fracture network generated by the infill well with the old well determines the subsequent fluid and oil-increasing performance of the disturbed well.The synergistic production or competitive relationship formed by fractures with different connectivity between the two wells determines the positive and negative effects of the interference.The paper also investigates the adaptation study of water injection huff and puff schemes for well groups with different connectivity,and demonstrated a potential yield increase of up to 10.85%under adaptation injection.This method of identifying well interference based on the production dynamics of affected wells and the subsequent corresponding water injection method provides valuable references for the selection of secondary oil recovery measures.

Data-driven optimization for fine water injection in a mature oil field

Based on the traditional numerical simulation and optimization algorithms,in combination with the layered injection and production"hard data"monitored at real time by automatic control technology,a systematic approach for detailed water injection design using data-driven algorithms is proposed.First the data assimilation technology is used to match geological model parameters under the constraint of observed well dynamics;the flow relationships between injectors and producers in the block are calculated based on automatic identification method for layered injection-production flow relationship;multi-layer and multi-direction production splitting technique is used to calculate the liquid and oil production of producers in different layers and directions and obtain quantified indexes of water injection effect.Then,machine learning algorithms are applied to evaluate the effectiveness of water injection in different layers of wells and to perform the water injection direction adjustment.Finally,the particle swarm algorithm is used to optimize the detailed water injection plan and to make production predictions.This method and procedure make full use of the automation and intelligence of data-driven and machine learning algorithms.This method was used to match the data of a complex faulted reservoir in eastern China,achieving a fitting level of 85%.The cumulative oil production in the example block for 12 months after optimization is 8.2%higher than before.This method can help design detailed water injection program for mature oilfields.

Three-dimensional physical simulation and optimization of water injection of a multi-well fractured-vuggy unit

With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.

Adaptability research of hydrofoil surface water injection on cavitation suppression

To study the effectiveness of hydrofoil surface water injection on cavitation suppression,the unsteady cavitation flow field around the NACA0066 hydrofoil at attack angle of 6°was simulated by the modified RNG k-εturbulence model combined with the full-cavitation model.The structure of cavitation flow field and the hydrodynamic performance of hydrofoil were analyzed at the cavitation number of 0.85,0.70,0.55,respectively.The results show that barriered by the jet,the momentum of the reentrant jet was reduced;The development of cavitation and the strength of cavity shedding were weakened to some extent.Cavitation suppression effect was very obvious in the cavitation conditions with the cavitation number of 0.7 and above when the injection position was at 37% chord length from the hydrofoil leading edge and the jet-flow ratio kept 0.3.Time-averaged lift and drag coefficient were reduced,and the lift-drag ratio increased in water injection conditions.

Seismic Response Analysis of Portal Water Injection Sheet Pile

To further the study on the newly developed portal water injection sheet pile under static loads, in this paper, by adopting the nonlinear calculation module of FEM software ANSYS, a model for the interaction between the soil and the sheet piles is set up, and the seismic response analysis for this type of space-retaining structure is performed. The effects of the embedded depth and the distance between the front pile and the back pile on the dynamic characteristics of the portal water injection sheet pile are studied.

Simulation and Modelling of Water Injection for Reservoir Pressure Maintenance

Water injection has shown to be one of the most successful,efficient,and cost-effective reservoir management strategies.By re-injecting treated and filtered water into reservoirs,this approach can help maintain reservoir pressure,increase hydrocarbon output,and reduce the environmental effect.The goal of this project is to create a water injection model utilizing Eclipse reservoir simulation software to better understand water injection methods for reservoir pressure maintenance.A basic reservoir model is utilized in this investigation.For simulation designs,the reservoir length,breadth,and thickness may be changed to different levels.The water-oil contact was discovered at 7000 feet,and the reservoir pressure was recorded at 3000 pounds per square inch at a depth of 6900 feet.The aquifer chosen was of the Fetkovich type and was linked to the reservoir in the j+direction.The porosity was estimated to be varied,ranging from 9%to 16%.The residual oil saturation was set to 25%and the irreducible water saturation was set at 20%.The vertical permeability was set at 50 md as a constant.Pressure Volume Temperature(PVT)data was used to estimate the gas and water characteristics.

Mechanisms of remaining oil formation by water flooding and enhanced oil recovery by reversing water injection in fractured-vuggy reservoirs

To get a deeper understanding on the formation mechanisms and distribution laws of remaining oil during water flooding, and enhanced oil recovery(EOR) mechanisms by reversing water injection after water flooding, 3D visualization models of fractured-vuggy reservoir were constructed based on the elements and configuration of fractures and vugs, and typical fracture-vug structures by using advanced CT scanning and 3D printing technologies. Then, water flooding and reversing water injection experiments were conducted. The formation mechanisms of remaining oil during water flooding include inadequate injection-production well control, gravity difference between oil and water, interference between different flow channels, isolation by low connectivity channel, weak hydrodynamic force at the far end. Under the above effects, 7 kinds of remaining oil may come about, imperfect well-control oil, blind side oil, attic oil at the reservoir top, by-pass residual oil under gravity, by-pass residual oil in secondary channel, isolated oil in low connectivity channel, and remaining oil at far and weakly connected end. Some remaining oil can be recovered by reversing water injection after water flooding, but its EOR is related to the remaining oil type, fracture-cavity structure and reversing injection-production structure. Five of the above seven kinds of remaining oil can be produced by six EOR mechanisms of reversing water injection: gravity displacement, opening new flow channel, rising the outflow point, hydrodynamic force enhancement, vertically equilibrium displacement, and synergistic effect of hydrodynamic force and gravity.

Using cyclic alternating water injection to enhance oil recovery for carbonate reservoirs developed by linear horizontal well pattern

In view of high water cut and low oil recovery caused by the unidirectional flow in linear pattern of horizontal wells for the carbonate reservoirs in the Middle East,this paper provides a novel approach to improve oil recovery by converting linear water injection to cyclic alternating water injection patterns including cyclic alternating water injection with apparent inverted seven-spot pattern or apparent five-spot pattern and cyclic differential alternating water injection.The main advantage of using this strategy is that the swept efficiency is improved by changing injection-production streamlines and displacement directions,which means displacement from two different direction for the same region during a complete cycle.This technology is effective in increasing the swept efficiency and tapping the remaining oil,thus resulting in higher oil recovery.Field application with three new patterns in a carbonate reservoir in the Middle East is successful.By optimizing injection and production parameters based on the cyclic alternating well pattern,the test well group had a maximum increase of daily oil production per well of 23.84 m^(3) and maximum water cut drop of 18%.By further optimizing the distance(keep a long distance)between the heels of injection and production wells,the waterflooding performance could be better with water cut decreasing and oil production increasing.

Slim Water Injection Nozzle for Silicon Wafer Wet Cleaning Bath

In order to effectively and quickly clean the surface of semiconductor silicon wafers, the fluid flow is one of the significant issues. For a batch-type silicon wafer wet cleaning bath, a slim water injection nozzle consisting of a dual tube was studied, based on theoretical calculations and experiments. A thin inner tube was placed at the optimum position in the water injection nozzle. Such a simple design could make the water injection direction normal and the water velocity profile symmetrical along the nozzle. The water flow in the wet cleaning bath was observed using a blue-colored ink tracer. When the nozzle developed in this study was placed at the bottom of the bath, a fast and symmetrical upward water stream was formed between and around the wafers.

Laboratory-Scale Evaluation of Single Analyte Bacterial Monitoring Strategies in Water Injection Systems

Microbial activity is the cause of a variety of problems in water injection systems, e.g., microbial corrosion, plugging, and biofouling. Efficient monitoring of Saudi Aramco’s vast water injection system requires the development of online and automated technologies for monitoring microbial activities in the system. A previous system review and technology screening has identified five single-analyte strategies [1], which were evaluated in this study with a laboratory-scale setup to determine their applicability for automated determination of microbial activity in the injection water system. Four of the five single-analyte measuring principles tested in the laboratory setup were deemed less suitable for automation and/or reliable for use in the detection of microbial activity in the company injection water system. These four principles were: luminescence assay for adenosine-5’-triphosphate (ATP), detection and electrochemical measurements of H2S, determination of pH by electrochemical sensor, and measurement of oxidation-reduction potential (ORP). The strategy of staining cells with fluorescent DNA dyes, followed by quantification of fluorescence signals, was identified to hold, with proper optimization of DNA staining and fluorescence detection, a very promising potential for integration in automated, online sensors for microbial activity in the injection water system.

The Effect of the Sinking of Isotope Grains in Water Injection Profile Logging

In the process of oil field exploitation, radioactive isotope tracer water injection profile logging is a main method to determine the water-intake capacity of the target intervals. For those general water injection wells, whose perforated intervals are beyond the tubing shoe, the sinking speed of isotope grains is related to the density and salinity of the injection water and the tubing dimension. We studied the motion of the isotope grains in the water injection wells by both theoretical calculation and field experiment. The result shows that if the water injection quantity is over 20 m＆3/d, and the density of the isotope grains, whose diameter is 100-600 μm, is 1.06 g/cm^3, then the logging technique for this kind of water injection wells will be appropriate. Whether water injection profile logging is successful in the well, whose perforated intervals are beyond the tubing shoe, depends on the sinking speed of the tracer grains.

Effect of heterogeneity on engineered water injection in carbonates using five-spot sector model:A numerical study

One of the promising and emerging enhanced oil recovery techniques in both sandstones and carbonates is engineered water injection(EWI).However,few studies discussed the field-scale applications of this technique in heterogeneous carbonate formations.This paper is an extension of our previous work of the EWI technology at core-scale.This research numerically investigates heterogeneity effect on EWI technique in carbonates at field-scale using five-spot models.Three synthetic five-spot sector models were considered including homogeneous,heterogeneous with permeability channeling,and heterogeneous with gravity underride.The results showed that EWI improves both volumetric and displacement sweep efficiencies compared to conventional formation water injection(FWI)for all models investigated.Also,tracer method is recommended for better estimation of volumetric sweep efficiency as opposed to fractional flow method.Moreover,secondary EWI outperforms other techniques including secondary FW and tertiary EWI.In addition,the observed delay in tertiary EWI can be reduced by increasing well injection pressure and sulfate concentration in the engineered water.An optimum sulfate concentration of 25,000 ppm is recommended for achieving the highest oil recovery by EWI.This study gives more insight into understanding the performance of the EWI technique at field-scale.Recommendations for boosting the performance of this technique have been discussed,which assure more certainty and lower risk.

Inhibition Effect of Water Injection on Afterburning of Rocket Motor Exhaust Plume

One of the most important characteristic signatures of the exhaust plume from rocket motor is the aflerbuming phenomenon, and the injected water into the plume could inhibit the afterburning. The calculation model for the gas-liquid multiphase flow field with chemical reaction in the plume is built. By inducing the energy source terms caused by the vaporization of liquid water, condensation of the vapor and chemical reaction in the energy equation, the gas-liquid multiphase flow field and the afterburning phenomenon are calculated in a coupling way. Mixture multiphase flow model is used to calculate the gas-liquid flow field, and the vaporization mechanism is used to investigate the water vaporization process. The temperature contours are obtained and accord well with the experimental photos. The mass fraction contours of primary species are obtained, which can indicate the extent of inhibition effect of water injection on the afterburning phenomenon in the plume. When water is injected into the plume, the region of aflerburning reduces a lot, and temperature on the ground wall declines rapidly, which can decrease the ablation of the combustion gas to the launch ground.

Placement of a Jejunal Feeding Tube via an Ultrasound-Guided Antral Progressive Water Injection Method

Background： Jejunal feeding tube allows the nutrition of critical care patients more easy and safe. However, its placement remains a challenge. This study aimed to introduce a jejunal feeding tube through an ultrasound-guided antral progressive water injection method and subsequently to examine its efficacy. Methods： Between April 2016 and April 2017, 54 patients hospitalized in the Department of Critical Care Medicine, Peking Union Medical College Hospital, China who needed nutritional support through a jejunal feeding tube were recruited for this study. Patients who applied ultrasound-guided antral progressive water injection method were classified into the experimental group. Patients who applied conventional method were registered as control group. Results： No significant differences were found in age, body mass index, and Acute Physiology and Chronic Health Evaluation score, but a significant difference in operation time was found between the experimental group and the control group. Of the 24 individuals in the control group, 17 displayed clear catheter sound shadows once the tube entered the esophagus. In comparison, of the 30 individuals in the experimental group, all harbored catheter sound shadows through the esophageal gas injection method. Subsequent observation revealed that in the control group （via ultrasonographic observation）, 15 individuals underwent successthl antral tube entry, for a success rate of 63%. In the experimental group （via antral progressive water injection）, 27 individuals underwent successful antral tube entry, for a success rate of 90%. There was a significant difference between the success rates of the two groups （x2 = 5.834, P= 0.022）. Conclusion： The antral progressive water injection method for the placement of a jejunal feeding tube is more effective than the traditional ultrasonic placement method.

Effect of water injection on the cavitation control:experiments on a NACA66(MOD)hydrofoil

The objective of this work is to investigate experimentally controlling cavitating flow over NACA66(MOD)hydrofoils by means of an active water injection along its suction surface.The continuous water vertically jets out of the chamber inside the hydrofoil through evenly distributed surface holes.Experiments were carried out in cavitation water tunnel.using high-speed visualization technology and the particle image velocimetry(PIV)system to study the sheetlcloud cavity behaviors.We studied the effects of this active control on cavity evolution with four kinds of jet flow at two different jet positions.We analyzed the effect of water injection on the mechanism of the cavitating flow control.The results were all compared with that for the original hydrofoil without jet and show that the active jet can effectively suppress the sheet/cloud cavitation characterized by shrinking the attached cavity size and breaking the large-scaled cloud sheding vortex cavity into small-scaled ones.The optimum effectiveness of cavitation suppression is affected by the jet flow rates and jet positions.The water injection at flow rate coefficient 0.0245 with the jet position of 0.45C reduces the maximum sheet cavity length by 79.4%and the cavity shedding is diminished completely,which gives the most superior effect of sheet cavitation suppression.The jet blocks the re-entrant jet moving upstream and weakens the power of re-entrant jet and thus restrains the cavitation development effectively and stabilizes the flow field.

TWO－PHASE FLOW FOR A HORIZONTAL WELL PENETRATING A NATURALLY FRACTURED RESERVOIR WITH EDGE WATER INJECTION

This paper examines the two-phase flow for a horizontal well penetrating a naturally fractured reservoir with edge water injection by means of a fixed streamlinemodel,The mathematical model of the verical two-dimensional flow or oil-water for a horizontal well in a medium with double-porosity is established ,and whose accuratesolutions are obtained by using the characteristic method .The saturation distributionsin the fractured system and the matrix system as well as the formula of the time of water free production are presented .All these results provide a theoretical basis and a computing method for oil displacement by edge water from naturally fracturedreservirs.

Characterization of pore volume of cumulative water injection distribution

Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency.A method to characterize the distribution of pore volume of cumulative water injection is proposed in this paper,and it is verified by a five-spot water flooding streamline simulation model.The logarithmic relation between pore volume of cumulative water injection and water saturation is established by regression.An inflection point and limit point of cumulative water injection pore volume are identified.Current simulation model indicates inflection point appears after 2e5 pore volume(PV)injection,and limit point appears after 15e25 PV injection.Both inflection and limit point vary in different regions of reservoir.

TWO－PHASE FLOW FOR A HORIZONTAL WELL PENETRATING A NATURALLY FRACTURED RESERVOIR WITH EDGE WATER INJECTION

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