Plugging System Research Articles

Evaluation of Deep Migration Performance of Large Size Elastic Profile Control Particles

In this paper, aiming at a millimeter scale large size elastic profile control particle used in field application, an evaluation experiment on the performance of deep migration was designed, the corresponding fracture model and replacement device were made and the relevant data solution method was proposed. The effects of the fracture width, particle mass fraction and particle injection velocity on the deep migration ability of the particles were evaluated respectively. At the same time, the plugging ability of the fractured filling particles for the water flow was evaluated. The fracture width has a great influence on the pressure threshold of the particle through the fracture, while the particle mass fraction and displacement injection velocity have a certain influence on the pressure threshold, but it is not very obvious. The particle plugging system is very poor in the ability of plugging and diversion. The water film bridge is formed in the interval between fractures and has great permeability to water flow. Compared with rigid particles, elastic particles increase the deep migration ability, but the pressure capacity of plugging is weakened, so it needs to be combined with other profile control systems in practical application.

Development of a High-Temperature-Resistant Polymer-Gel System for Conformance Control in Jidong Oil Field

Summary The PG Reservoir in Jidong Oil Field is at a depth of approximately 4500 m with an extremely high temperature of approximately 150°C. The average water cut has reached nearly 80%, but the oil recovery is less than 10% after only 2 years of waterflooding process. It is of great importance to develop a high-temperature-resistant plugging system to improve the reservoir conformance and control water production. An in-situ polymer-gel system formed by the terpolymer and a new crosslinker system was developed, and its properties were systematically studied under the condition of extremely high temperature (150°C). Suitable gelation time and favorable gel strength were obtained by adjusting the concentration of the terpolymer (0.4 to 1.0%) and the crosslinker system (0.4 to 0.7%). An increase of polymer and crosslinker concentration would decrease the gelation time and increase the gel strength. The gelant could form continuous 3D network structures and thus have an excellent long-term thermal stability. The syneresis of this gel system was minor, even after being heated for 5 months at the temperature of 150°C. The gel system could maintain most of the initial viscosity and viscoelasticity, even after experiencing the mechanical shear or the porous-media shear. Core-flow experiments showed that the gel system could have great potential to improve the conformance in Jidong Oil Field.

A high-temperature plugging system for offshore heavy oil thermal recovery.

There are many heavy oil reservoirs in offshore oilfields in China. Steam and multiple thermal fluid stimulation technologies are of increasing interest and have been applied to an increasing number of projects. During the stimulation or displacement of heavy oil reservoirs during thermal recovery, several factors, such as reservoir heterogeneity, are prone to cause channeling phenomena and affect the thermal recovery effect of steam stimulation. According to the unique requirements for the stimulation of multiple thermal fluids for offshore heavy oil, this study used transmission, blocking and relieving, heat resistance and a comprehensive evaluation of parallel sand tube experiments to conduct a screening evaluation of plugging systems for the stimulation of multiple thermal fluids, screen out a commonly used plugging agent in the current stage and propose corresponding guidance for the selection basis. The results show that foam, gel, foam gel and temperature-sensitive gel systems have a good transmission performance, whereas the oil sludge exhibits a poorer performance. The phenolic resin system exhibits great plugging properties, followed by oily sludge, temperature-sensitive gel, gel, foam gel and foam. Considering about washing resistance properties, phenolic resin system shows the best quality, followed by oily sludge and temperature-sensitive gel. The oily sludge system brings the best performance in plugging a high-permeability channel than phenolic resin gel and temperature-sensitive gel.

New type plugging particle system with high temperature & high salinity resistance

A new-type plugging coated particle system was investigated which is applied in high temperature & salinity reservoir, the temperature up to 300℃ and salinity up to 250,000mg/L. To analyze these factors, based on adhesion feature of the particle, a series of experiments were performed to investigate properties of particle and its suspension system, including dynamic plugging experiments, etc. The results showed that the particles can adhere together under certain temperature up to 140℃. Moreover, the particle suspension, including HPG system and foam system, were screened based on suspending time. In addition, we selected four parameters, including salinity, injection rate, permeability and mass fraction, to measure plugging ability of system. Meanwhile, the visual microscopic models and glass sand-pack models were designed to observe directly particle flow in the porous media. Finally, the force analysis of particles at some special locations in the models was simulated by COMSOL Multiphysics. Experimental results confirmed the essential characters of new-type particle and indicate that this plugging system had excellent plugging performance in high temperature & salinity environment. The particle migration had strong correlation with permeability and the particle had impacted on the original structure of mineral. The process of packing was accelerated and repeated. Besides, keeping the particle single and improving material strength would promote plugging effects. The evaluation and mechanism research of new type plugging particle could provide guidance for plugging agent selection in high temperature and field development project designing.

Combining carbon dioxide and strong emulsifier in-depth huff and puff with DCA microsphere plugging in horizontal wells of high-temperature and high-salinity reservoirs

The profile control and water shutoff are still considered as technical problems for high-temperature and high-salinity reservoirs. A composite technique combining carbon dioxide and strong emulsifier in-depth huff and puff with water shutoff in the horizontal wells of high-temperature and high-salinity reservoirs was proposed. The composite technique comprised a strong emulsifier technique, a water shutoff agent technique, and technical injection of working fluid slug. The strong emulsifier technique included emulsifier screening. The ability of strong emulsifier served as the performance index. The strong emulsifier had two roles. When the strong emulsifier reached the oil, the entire system could be emulsified to activate the plugging system in situ and in real time. During the migration of oil and water, the emulsion system could improve volumetric sweep efficiency and microscale displacement efficiency. Carbon dioxide had a good emulsifying capability. The water shutoff agent technique included research on the high-temperature resistance and high-salinity resistance of polymer microspheres. The residual resistance coefficients of positive injection and back injection of polymer microspheres were still greater than 2. The working fluid included the slug of the system of polymer microspheres, the slug of the strong emulsifier and the slug of the carbon dioxide. Three kinds of slugs could improve volumetric sweep efficiency and microscale displacement efficiency during production. The key process of the proposed technique was the sequential injection of carbon dioxide and the strong emulsifier into the producer well of horizontal well. Upon injecting of polymer microspheres of the water shutoff agent, the microspheres aggregated to physical plugging and bridging by the effect of covalent bonds on one another after reaching the deep reservoir. The carbon dioxide and strong emulsifier were shut by the microspheres in the high-permeability formation. When water (bottom water, edge water, or injected water) approached the oil well along the high-permeability zone, the carbon dioxide and strong emulsifier would be carried by the water into the middle-permeability and low-permeability zone with higher oil saturation during production. Optimizing the injection method of the working fluid slug, a composite technique that combined carbon dioxide and a strong emulsifier with polymer microspheres was also proposed. Laboratory results showed that the rate of enhanced oil recovery increased by 38.50% based on water flooding recovery (10.00%) by using carbon dioxide in-depth huff and puff and polymer microsphere plugging after the first round. The rate of enhanced oil recovery increased by 17.75% based on the water flooding recovery of the first round by using carbon dioxide and strong emulsifier in-depth huff and puff and polymer microsphere plugging. In this paper the results of physical simulation experiments further prove that combining carbon dioxide and strong emulsifier in-depth huff and puff with divinylbenzene-co-acrylamide (DCA) microsphere plugging is a potential technical direction for controlling water cut and increasing oil recovery in horizontal well of high-temperature and high-salinity reservoirs.

Integrated Technology of Water Plugging and Acidizing of Hydrofractured Oil Wells

An integrated technology combining water plugging and acidizing in the same flooded oil well is studied with the goal of controlling the water content of the oil and attaining a comprehensive synergy. For this, a micro- and macro-fracture porosity model and four models with other kinds of fractures are built. The feasibility of application of gel water plugging system in this integrated technology is evaluated. The experimental results show that the gel system is effective in high-permeability interlayer plugging (plugging degree >99%), but not very effective in low-permeability interlayers. Multi-slug injection reduces the impact of subsequent acidizing on the effectiveness of the pugging material. At the same time, the degree of oil recovery by displacement with water for the fracture porosity model is not high, but after polymer plugging system injection, recovery increases, reaching more than 60%. The proposed integrated technology was applied in two wells in the Chongqing oilfield. Oil production of each well increased on an average by 1 ton/day for more than one year.

Water Shutoff and Profile Control with the Combination of Single Fluid and Double Fluids

Both the single fluid and double-fluid method for water shutoff and profile control have their limitations. If the two kinds of working fluids are used in combination for water shutoff and profile control, each of them exhibits its own plugging capability while they can form plugging materials when they contact and react with each other. This method can be used as a plugging system in the formations, eliminating the low utilization ratio and huge waste of the single or double-fluid chemicals. It can enhance the plugging capability and improve the water shutoff and profile control results. The single and double fluid (SAD) system has been proved satisfactory in the field tests of conventional chemical water shutoff and profile control, high temperature chemical water shutoff and high temperature profile control and channeling-plugging in thermal recovery wells. The economic benefits are remarkable from the field tests of 14 wells.

Visualization Experimental Study on Organic-Inorganic Crosslinked Plugging System Plugging

As a compound modifying and flooding agent, the organic-inorganic crosslinked plugging system which is mixed by gel and silicide according our experimental study, formed integral crosslinked system at high temperature and varied in a broad range gelling time by regulate concentration of organic-inorganic crosslinked plugging system. It exhibits excellent thermostability, shear properties, plugging performance and washable characteristic. In this visual experiment, the organic-inorganic crosslinked plugging systems injection, waterflooding effect and sealing capacity on homogeneous reservoir and heterogeneous reservoir are all exhibited clearly. The results of experiment show that organic-inorganic crosslinked plugging system has a good injectivity and water plugging performance. Depth of injection has an important effect on water-flooding situation, further influencing the increasement of recovery factor. Before the injection of Organic-Inorganic Crosslinked Plugging System, we inject some viscosity reducer, such as foam solution which reducing the deep oil viscosity, keeping the high recovery efficiency and preventing the mistaken plugging.

용탕자중공급 PFC법을 이용한 의료용 동위원소 Mo-99 조사타겟용 우라늄박판 제조공정개발

In order to complement the drawbacks of quartz crucible such as fragile-like break and melt-leakage through open slit nozzle, a new PFC system has been developed using a common graphite crucible and plugging system. The u melt is fed on to the rotating a roll through slit nozzle by self-gravity. The new equipment was designed and manufactured successfully. An effort for optimizing all related parameter has been made. Then using the optimized parameters about 10 meters u foil having very thin thickness, which meets the target thickness of 130 <TEX>${\mu}m$</TEX> and enough width more than 60 mm could be made. The thickness homogeneity set improved, due to the lower eddy flowing of the melt flow the self-gravity feeding system.

Bacteriogenic Mineral Plugging

Abstract A novel permeability reduction process has been developed to control fluid flow in porous media. The procedure generally, involves use of bacteria to actively precipitate calcium carbonate as a mineral plugging and cementing agent. This process may be suitably employed to enhance the recovery of oil from oil reservoirs, cement unconsolidated sand underground, or to control the flow of contaminants in an aquifer. Introduction In heavy oil fields, water responds to pumping more readily than viscous oil, so wells on primary production commonly water out after low recoveries of the oil-in-place. This is a serious problem that can occur gradually over several years, or be a catastrophic event when water directly underlies the oil bearing zone. For both of these situations, control of excess water production may be accomplished by selectively plugging zones of water encroachment(1,2). A number of selective plugging systems for reservoir conformance correction have been developed. Chemically cross-linked polymers are available for use, but are expensive in pure form and perform unpredictably under reservoir conditions(3). Similarly, insoluble biopolymers and biomass generated by injected bacteria or by indigenous micro-organisms can be used to selectively plug off zones of high water permeability(1,4,5). The concept has been demonstrated in laboratory experiments; however, poor results have been obtained in field applications of microbial plugging systems(6). More recently, work has focussed on inorganically precipitated mineral plugs using polysulfides(7) or colloidal silica(8). This is expected to improve plug stability and extend use of the technology to more sophisticated production modes. The same advantages may be afforded by a novel bacteriogenic mineral plugging system developed to control fluid flow in porous media. Bacteriogenic mineral plugging involves using injected or indigenous micro-organisms to precipitate authigenic minerals in high permeability water channels. This can be accomplished byusing bacteria as passive nucleation sites while injecting an appropriate solution to oversaturate formation water with respect to a certain mineral phase,stimulating specific bacteria whose metabolic activity will bring about a mineral oversaturation, ora combination of the two processes. Precipitation of the mineral would be expected to selectively plug off the water bearing zones allowing oil production to continue (until further water breakthrough occurred). Of the various minerals that bacteria can precipitate, calcium carbonate is a particularly good candidate for bacteriogenic mineral plugging. Bacteria have been implicated as the causative agents for carbonate precipitation in a number of laboratory and field investigations(9-11). In addition, most heavy oil reservoir formation waters in Western Canada are near saturation with calcite(12). Consequently, stimulation of bacteria that generate alkaline conditions would promote an increase in carbonate concentrations and induce calcite precipitation(13). In this paper, experiments are described using bacteria to increase pH and precipitate calcium carbonate as a mineral plugging and cementing agent. Experimental Materials The bacterial strain used was Bacillus pasteurii NRS 673. Sand used for this work was number 16 silica. Whisling, Illinois. Analysis provided by the company indicated packed cores would have a 0.37 porosity with a permeability of 2.5 Darcies. Reservoir sand for enriched cultures of indigenous bacteria was also used.

Bacteriogenic Mineral Plugging

Abstract A novel permeability reduction process has been developed to control fluid flow in porous media. The procedure generally involves use of bacteria to actively precipitate calcium carbonate as a mineral plugging and cementing agent. This process may be suitably employed to enhance the recovery of oil from oil reservoirs, cement unconsolidated sand underground, or to control the flow of contaminants in an aquifer. Introduction In heavy oil fields, water responds to pumping more readily than viscous oil, so wells on primary production commonly waterout after low recoveries of the oil-in-place. This is a serious problem that can occur gradually over several years, or be a catastrophic event when water directly underlies the oil bearing zone. For both of these situations, control of excess water production may be accomplished by selectively plugging zones of water encroachment(1,2). A number of selective plugging systems for reservoir conformance correction have been developed. Chemically cross-linked polymers are available for use, but are expensive in pure form and perform unpredictably under reservoir conditions(3). Similarly, insoluble biopolymers and biomass generated by injected bacteria or by indigenous micro-organisms can be used to selectively plug off zones of high water permeability(1,4,5). The concept has been demonstrated in laboratory experiments; however, poor results have been obtained in field applications of microbial plugging systems(6). More recently, work has focussed on inorganically precipitated mineral plugs using polysulfides(7) or colloidal silica(8). This is expected to improve plug stability and extend use of the technology to more sophisticated production modes. The same advantages may be afforded by a novel bacteriogenic mineral plugging system developed to control fluid flow in porous media. Bacteriogenic mineral plugging involves using injected or indigenous rnicro-organisms to precipitate authigenic minerals in high permeability water channels. This can be accomplished by (i) using bacteria as passive nucleation sites while injecting an appropriate solution to oversaturate formation water with respect to a certain mineral phase, (ii) stimulating specific bacteria whose metabolic activity will bring about a mineral oversaturation, or (iii) a combination of the two processes. Precipitation of the mineral would be expected to selectively plug off the water bearing zones allowing oil production to continue (until further water breakthrough occurred). Of the various minerals that bacteria can precipitate, calcium carbonate is a particularly good candidate for bacteriogenic mineral plugging. Bacteria have been implicated as the causative agents for carbonate precipitation in a number of laboratory and field investigations(9–11). In addition, most heavy oil reservoir formation waters in Western Canada are near saturation with calcite(12). Consequently, stimulation of bacteria that generate alkaline conditions would promote an increase in carbonate concentrations and induce calcite precipitation(13). In this paper, experiments are described using bacteria to increase pH and precipitate calcium carbonate as a mineral plugging and cementing agent. Experimental Materials The bacterial strain used was Bacillus pasteurii NRS 673. Sand used for this work was number 16 silica. Whisling, Illinois. Analysis provided by the company indicated packed cores would have a 0.37 porosity with a permeability of 2.5 Darcies.

紫外線硬化型穴埋めインクおよびシステムの開発

紫外線硬化型穴埋めインクおよびシステムの開発

Characterization of Water Soluble Polymers by Ion Chromatography. I. Poly(Acrylamide-co-Sodium Acrylate)

Abstract The sodium counterion contents of a series of poly(acrylamide-co-sodium acrylate) copolymers of varying composition have been investigated by Ion Chromatography (IC). Sodium ion contents obtained by IC are comparable with values based on either elemental analysis or titration techniques. Therefore, IC results can be used to determine the degree of polymer hydrolysis. Since sodium ion can be quantified at ppm levels, this analysis is possible with solutions containing =20 ppm polymer. At such concentrations, there is no evidence for column plugging or excessive system backpressure. Ionic contamination from glass storage vessels can be significant at these dilutions, however. The results of polymer dialysis and sonication studies are included. This study has explored the effects of key polymer and IC variables on the determination of Na+ ion content of aqueous HPAM solutions. Good agreement with the results based on elemental analysis or an ion-exchange/titration technique was established. A good correlation was also obtained between the sodium ion content of replicated samples of HPAMs versus the degree of hydrolysis of these polymers. Thus the feasibility of using IC for compositional analyses of these water soluble polymers has been demonstrated. Refinement of the method should lead to improved precision and several useful applications. Based on the inherent attributes of ion chromatography (e.g. small sample size requirements, high precision, quick analysis times, etc.) IC should have wide applicability in studies of ionic water soluble polymer systems. Potential applications include investigation of polymer composition, polymer concentration, polymer adsorption, and effects of processes such as dialysis.