Bottom Water Reservoir Research Articles

Optimization and Performance Evaluation of Foam Discharge Agent for Deep Aquatic Condensate Gas Well

The block deep condensate gas reservoir in the basin in the southeast of the South China Sea is a bottom water reservoir and is producing in the late effusion, which faces problems such as scaling, condensate oil–water two-phase flow, and low temperature at the subsea wellhead. The mud line for this kind of gas-well has characteristics including high condensate content in low temperature, high downhole temperature, and injection with a foam discharge agent and scale inhibitor. In this article, the influence of low temperature and scale inhibitor is considered for the first time, and a dynamic liquid-carrying experiment for the optimization and performance evaluation of foam discharge agents was carried out according to these characteristics. The experimental results show that the optimized foam discharge agent, ZHY-01, has good resistance to high temperature and condensate oil, and the optimal concentration of the foam discharge agent is recommended to be 0.25%. Under this concentration, the liquid-carrying capacity of the foam discharge agent decreases slightly by 10.17% at low temperature. The scale inhibitor MA/AA reduced the liquid-carrying capacity by 11.86%, and the scale inhibitor PESA reduced the liquid-carrying capacity by 10.17%. The research results in this article have certain reference significance for the chemical screening and evaluation of the foam drainage gas production process in deep-water condensate gas wells.

Water Invasion Law and Water Invasion Risk Identification Method for Deep Sea Bottom-Water Gas Reservoir

This study analyzes the water invasion characteristics and water encroachment of the deep sea bottom-water gas reservoir (LS17 field) in the South China Sea for the purpose of developing horizontal wells. Gas-producing profile tests and a three-dimensional (3D) water invasion simulation are used to produce a quantitative analysis of the bottom-water cresting influence factors. On this basis, we establish a suitable risk identification method for the water influx of a deep bottom-water reservoir. The results show that: (1) During the development of a bottom-water gas reservoir, the water ridging is affected by reservoir heterogeneity, production system and heel–toe effect of a horizontal wellbore, and reservoir heterogeneity is the main influencing factor; (2) the horizontal–vertical ratio of the well area determines whether the gas well productivity will be affected by the risk of water invasion. The stronger the reservoir heterogeneity, the smaller the safety limit value of the horizontal–vertical ratio; (3) when the permeability differential increases gradually, the safety limit value of the transverse longitudinal ratio decreases in turn; (4) based on the relationship curve between permeability level difference and the safety limit value of the horizontal–vertical ratio in the well area, the horizontal–vertical ratio of the N1H well is far greater than the safety limit value. The well is at high risk of water invasion and should be developed by water control. In order to improve deep seabed water and gas reservoirs, water control development should be carried out in well areas with sufficient water energy and high water invasion risk. The water invasion characteristics of bottom-water gas reservoirs under different water control technologies (such as variable density screen technology, filling water blocking, breathable coated gravel technology, etc.) and production systems (periodic gas production technology) should be studied. The research results can not only judge the water invasion risk of deep seabed water and gas reservoirs under different permeability levels and gas production rates but also provide a reference for water control development of offshore and onshore bottom-water and gas reservoirs.

Research on the Water Production Tracking Method of Horizontal Well in Heavy Oil Reservoir with Bottom Water

Abstract At present, the model of heterogeneous fluid production in horizontal wells in bottom water reservoirs does not comprehensively consider the influence of parameters such as flow, length, and position of each production section, resulting in the distortion of interpretation results. Using the Green function and the Newman product method, this paper derives heterogeneous fluid production in horizontal wells in the bottom water heavy oil reservoir. The Stehfest numerical inversion algorithm was used to obtain the bottom fluid pressure solution of the horizontal well production in the bottom water heavy oil reservoir with the wellbore storage effect and skin effect. By drawing the typical chart of horizontal well test in sections, the new model can be divided into five typical flow stages: wellbore storage stage, transition stage, radial flow stage, linear flow stage, and late stable flow stage. Based on the interpretation of conventional parameters, such as permeability, well storage, and skin effect, the new model can further diagnose the parameters such as liquid production length, liquid production position, and liquid production volume of each horizontal section. The field application examples verify the validity of the research results and broad application prospects.

Flow Physics of Profile Control Fluids in Porous Media and Implications for Enhanced Oil Recovery: A Microfluidic Study

Novel profile control agents are constantly emerging in the field of enhanced oil recovery, contributing to the extension of a stable production period. However, evaluation performed through conventional core flow experiments is usually inadequate to reveal the in-depth mechanism of profile control agents. Besides, due to different operation and production modes, there is an urgent need for a specific experimental method applicable to horizontal wells in bottom water reservoirs. In this context, this paper describes two models tailored to bottom water reservoirs and investigates the flow characteristics and mechanisms of three water-shutoff agent types. At the pore scale, further study was carried out on the water-shutoff synergism between a gel and an emulsifier. The results show that the gel is present at the edge of the pore body, while the emulsion is blocked in the center of the pore body. Hence, gel that enters a water channel (main flow and accumulation area of emulsion) can cooperate with an emulsion to achieve high-strength water shutoff, making the bottom water that re-invades mainly break through at oil-rich areas. Compared with water shutoff with gel alone (randomly distributed in the breakthrough area), the synergism improves the gel’s ability to select flow channels, inhibits emulsifier channeling, and achieves a remarkable EOR effect.

Application of new geosteering technology in thin reservoir

Because some oilfields in China belong to the thin bottom water reservoir model, the actual drilling process is technically difficult. In order to ensure the maximum drilling operation of the target layer and the basic development effect of the oilfield, technicians should introduce advanced steering tools and study new geosteering technology to fundamentally ensure the exploitation quality of thin oil reservoirs.After exploring the introduction of new geological guidance technology in detail, this paper further explores the principle of new geological guidance technology, and summarizes the application strategy of new geological guidance technology combined with the development of thin-layer reservoir.

Numerical Simulation of Residual Oil Displacement in Offshore Strong Bottom Water Reservoir

Numerical Simulation of Residual Oil Displacement in Offshore Strong Bottom Water Reservoir

A Method for Calculating Oil Field Relative Permeability Curve by Using Water Drive Characteristic Curve in High Water Cut Stage

With the production of strong bottom water reservoir, it will soon enter the ultra-high water cut stage. After entering the ultra-high water cut period, the main means of stable production is liquid extraction. Large liquid volume has a certain impact on the physical property distribution and fluid seepage law of the oilfield. The relative permeability curve measured according to the industry standard is not used for the prediction of development indicators and the understanding of the dynamic law of the oilfield. In order to understand the characteristics of water drive law in high water cut stage of water drive oilfield, starting from the water drive characteristic curve in high water cut stage, the method for calculating the relative permeability curve is deduced. Through numerical simulation verification and fitting the actual production data, it is confirmed that the obtained relative permeability curve is in line with the reality of the oilfield, It can provide some guiding significance for understanding the production law and water drive law of strong bottom water reservoir in ultra-high water cut stage.

Identification of Interlayer in Strong Bottom Water Reservoir and Its Influence on Development Effect

X oilfield is located in Bohai Sea area, in which G oil formation is a typical drape anticline structure, which is composed of multiple sets of thick sandy conglomerate and multiple sets of argillaceous intercalation. From the perspective of development effect, muddy interlayer has a great impact on the oilfield. In this paper, through core identification and well logging identification, the electrical discrimination standard is summarized to identify the interlayer. Through statistics and analysis of the production performance of actual wells, the influence of muddy interlayer on the development performance of oil wells is summarized. This study provides guidance for the development of strong bottom water reservoirs with interlayer.

Correction to: Water Cone Dynamic Prediction of Bottom Water Reservoir Considering Oil-Water Interface Dynamic Change

Correction to: Water Cone Dynamic Prediction of Bottom Water Reservoir Considering Oil-Water Interface Dynamic Change

Study on oil-water interface of Budate fracture reservoir in each block of Suderte Oilfield

It is well known that in addition to bound water in the reservoir, formation water mainly exists in the form of edge water and bottom water. Fractured buried hill metamorphic rock reservoirs are generally bottom-water reservoirs. In fractured reservoirs, rock blocks are cut by fractures and oil and water are distributed in fractures. Due to the low capillary pressure of fractures, the oil-water transition zone is also small. In the same fault block, there is relatively uniform oil-water interface. And oil-water interface to judge correctly or not will directly related to the determination of oil-bearing area and effective thickness division and well placement, thus correctly determine the position of the oil-water interface of oil field development is of great significance, through the variation of oil-water interface also presumably or some guidance on the seismic section can't precisely divide the small fault.

The Research and Field Test of Life-Long Water Control Completion Technology in the Offshore Oilfield

In order to solve the problem of bottom water rapid coning in horizontal well development of sandstone bottom water reservoir in Offshore oilfield. Based on the analysis of the advantages and disadvantages of ICD and AICD water control completion technology. Life-long water control completion technology is studied. The life-long water control completion technology combines the advantages of ICD and AICD water control completion technology. In the initial stage, the high permeability section is suppressed to balance the liquid supply profile in the horizontal section of horizontal well. At later stages, it can automatically control liquid to constrain the high water section, which can slow down the water cut increase. Well W1 in H reservoir of X oilfield is the application of life-long water control completion technology well By comparing with production well in the same reservoir. The analysis shows that the life-long water control completion technology can restrain the rise of water cut in the process of horizontal well development, which is worthy of expanding the scale test. At the same time, it can provide reference for the development of similar offshore reservoirs.

The Effect of Interlayer on Water Cut Rise in a Bottom Water Reservoir

A bottom water reservoir is universal in all reservoirs in the world. In the exploitation process of the bottom water reservoir, because the reservoir is in complete contact with bottom water, the natural energy supply of the bottom water reservoir is sufficient. At the same time, in the production process, the pressure drop generated by the formation is mainly concentrated near the wellbore, which leads to a short period of waterless oil production, fast water breakthrough, and fast water cut rise, which seriously affects the overall recovery factor and increases the risk of oil filed exploitation. Since the distribution of an interlayer enhances the heterogeneity of the reservoir, it has a prominent impact on the flow of oil and water in the bottom water reservoir. However, people know little about the impact of the interlayer on the bottom water reservoir. In this paper, the mathematical model of two-phase flow in the bottom water reservoir with the interlayer is proposed, and the numerical solution of the model is obtained by a finite element method. The influence of the distribution of the interlayer on the water cut rising law of the bottom water reservoir is analyzed. The results show that the bottom water is blocked by the interlayer and its own gravity and the rising height of the bottom water is limited, so that the interlayer has a significant inhibitory effect on the coning of the bottom water. The closer the interlayer is to the oil-water interface, the faster the water cut will rise; the narrower the interlayer is, the faster the bottom water ridge will advance; when the width of the interlayer is the same as that of the reservoir, the water cone will not appear; the higher the permeability of the interlayer is, the faster the upper body of the water cut will be; when the permeability of the reservoir and the interlayer is over 1000, the influence of the interlayer on the water cut rise is not obvious; the thickness of the interlayer on the water cut rise law has little effect. Finally, through the case analysis, it is proposed that the new horizontal wells should be arranged in the position where the interlayer develops. The findings of this study can help for the better understanding of control laws of the interlayer on the bottom water and providing a crucial theoretical basis for the development of the bottom water reservoir.

Novel preformed gel particles with controllable density and its implications for EOR in fractured-vuggy carbonated reservoirs

The pre-crosslinked gel particles has been perceived as an important alternative to improve oil recovery from fractured-vuggy carbonate reservoirs. However, it remains a great challenge for the applications in high temperature and high salinity reservoirs. In this context, we firstly developed novel preformed gel particles with controllable density (PGPCD) which can be used at high temperature (140 °C) and high salinity (250 g/L) fractured-vuggy carbonate reservoirs for in-depth profile control and displacement. Then, the swelling property, toughness, injectivity, EOR potential and EOR mechanisms of PGPCD were investigated. Experimental results show that PGPCD has favorable swelling ability, toughness, and controllable density due to the introduction of sodium montmorillonite and modified foamed acrylate rubber (ACM) powders. Moreover, PGPCD has favorable injectivity, and can mitigate water channeling in the form of “filling accumulation”, “bifurcation accumulation”, and “necked accumulation”. After the treatment, PGPCD achieves incremental oil recovery in a range of 16%–26% of original oil in place. Taken together, our findings suggest the role of PGPCD in promoting the incremental oil recovery at high temperature and high salinity reservoirs, especially in fractured-vuggy carbonate bottom water reservoirs.

Water Cone Dynamic Prediction of Bottom Water Reservoir Considering Oil-Water Interface Dynamic Chance

Water Cone Dynamic Prediction of Bottom Water Reservoir Considering Oil-Water Interface Dynamic Chance

Reservoir and Wellbore Flow Coupling Model for Fishbone Multilateral Wells in Bottom Water Drive Reservoirs

AbstractNowadays, different types of complex production wells are applied in challenging reservoirs in order to maximize oil recovery. A representative application is the fishbone multilateral horizontal wells, which have advantages of expanding the drainage area information and reducing the pressure loss in the long single lateral wellbore. This paper investigated the performance of fishbone wells and derived a wellbore and reservoir flow coupling model for fishbone multilateral wells in the bottom water reservoirs. The new model considered plenty of parameters that may have significant impacts on productivity and pressure drop in the well, including the fishbone structure, the main and branch wellbores’ length, the spacing distance of the branch wellbores, wellbore radius, and preformation parameters. Furthermore, a sensitivity analysis example by the numerical method is presented in this paper. Compared with other models, our coupling model, when it is degraded to horizontal well, is more consistent with the results of actual field situation. In another comparative analysis, the results of the new model with branches show a good match with the numerical simulation results by software. The proposed method in this paper can be used as a valuable tool to analyze the productivity, wellbore inflow profile, and pressure profile of the fishbone multilateral wells in the bottom water reservoir.

Deepening research on the distribution characteristics of interlayers in marine sandstone reservoirs

At present, CNOOC has a large number of bottom water reservoirs developed by horizontal wells in the production oilfields, but the overall geological reserves of the oilfields are relatively low. The biggest problem facing this type of reservoir development and adjustment and tapping is the separation of the reservoir. The identification and quantitative characterization of the development characteristics of interlayer space. Therefore, in this paper, by formulating standards for the identification of barriers and intercalations, in-depth study of the profile and plane distribution characteristics of barriers and intercalations, and carrying out studies on the anatomy and characterization of the distribution of marine sandstone reservoirs. The results of the study show that the distribution of the study area on the profile is mainly composed of interlayers in the southwest and northwest of the legal person of the study area, with good connectivity and continuity. The distribution of interlayers on the plane is mainly muddy. Mainly with mezzanine, the research results in this paper are helpful to improve the accuracy of the anatomy of marine sandstone reservoir stacking relationship and the characterization accuracy of interlayer distribution, and improve the development effect of this type of reservoir.

Research and Application of Precision Characterization Technology for Numerical Simulation of Side Bottom Water Reservoir

In this paper, according to the technical requirements of accurate characterization of middle and bottom water reservoir model in reservoir numerical simulation, three technical means have been used to solve the difficult problem that puzzles the technicians. The first is to establish a mixture of analytical and numerical water bodies to accurately characterize the side water energy and at the same time to reduce the effective grid to improve the operation speed of the model; the second is to solve the problem of oil reservoir simulation in long time and stratified injection wells. The application of these characteristic technologies has played a good technical support role in the high water cut development period.

北特鲁瓦底水油藏水平井分段酸压技术应用研究

北特鲁瓦底水油藏水平井分段酸压技术应用研究

Analysis of Factors Influencing Shut in Pressure Cone in Offshore Strong Bottom Water Reservoir

X oilfield is an offshore strong bottom water reservoir with water cut up to 96% at present, and liquid extraction has become one of the main ways to increase oil production. However, the current liquid production of the oilfield reaches 60,000 m3/d due to the limitation of offshore platform, well trough and equipment, the oilfield is unable to continue liquid extraction. In order to maximize the oil production of the oilfield, it is necessary to study the strategy of shut in and cone pressure. Through numerical simulation, this paper analyzes the influence of different factors, such as crude oil density, viscosity, reservoir thickness, interlayer, permeability and so on, on the drop height of water cone and the effect of precipitation and oil increase after well shut in. At the same time, the weight of each factor is analyzed by combining the actual dynamic data with the fuzzy mathematics method, and the strategy of well shut in and cone pressure is formulated for the offshore strong bottom water reservoir. It provides the basis and guidance for the reasonable use of shut in pressure cone when the reservoir with strong bottom water meets the bottleneck of liquid volume.

An optimization method of horizontal well completion control water and sand

With the development and maturity of horizontal well drilling and completion technology, horizontal wells are widely used in various reservoirs and have achieved good development results. Due to horizontal wells in the reservoir through a long distance, horizontal section of the reservoir physical property heterogeneity, water avoidance height difference and horizontal wellbore flow with toe effect, leading to production pressure difference and water breakthrough time in all parts of the shaft is different, the level of sand and bottom water cresting is strong heterogeneity, oil well early water breakthrough and local a large amount of sand production, the serious influence of horizontal well production and development of comprehensive benefits. In this paper, based on the prediction model of critical production pressure difference of sand production in horizontal wells and the prediction model of water appearance time of horizontal Wells in bottom water reservoir, the critical production pressure difference and water appearance time of sand production in each micro-element section are quantitatively determined along the horizontal well section, so as to form a design method of horizontal well completion that takes water and sand control into account. And ICD horizontal well completion method as the research object, water breakthrough time, yield as the optimization goal, control sand as constraint conditions, with each section down into the number of ICD string and nozzle sizes as design variables, the ICD horizontal well completion parameters established multi-objective optimization model, obtained the comprehensive consideration of water control sand control effect of the optimal ICD completion program.