The efficiency of gas injection into low-permeability multilayer hydrocarbon reservoirs

The efficiency of gas injection for developing terrigenous deposits within a multilayer producing object is investigated in this article. According to the results of measurements of the 3D hydrodynamic compositional model, an assessment of the oil recovery factor was made. In the studied conditions, re-injection of the associated gas was found to be the most technologically efficient working agent. The factors contributing to the inefficacy of traditional methods of stimulating oil production such as multistage hydraulic fracturing when used to develop low-permeability reservoirs have been analysed. The factors contributing to the inefficiency of traditional oil-production stimulation methods, such as multistage hydraulic fracturing, have been analysed when they are applied to low-permeability reservoirs. The use of a gas of various compositions is found to be more effective as a working agent for reservoirs with permeability less than 0.005 μm2. Ultimately, the selection of an agent for injection into the reservoir should be driven by the criteria that allow assessing the applicability of the method under specific geological and physical conditions. In multilayer production objects, gas injection efficiency is influenced by a number of factors, in addition to displacement, including the ratio of gas volumes, the degree to which pressure is maintained in each reservoir, as well as how the well is operated. With the increase in production rate from 60 to 90 m3 / day during the re-injection of produced hydrocarbon gas, this study found that the oil recovery factor increased from 0.190 to 0.229. The further increase in flow rate to 150 m3 / day, however, led to a faster gas breakthrough, a decrease in the amount of oil produced, and a decrease in the oil recovery factor to 0.19. Based on the results of the research, methods for stimulating the formation of low-permeability reservoirs were ranked based on their efficacy.

The efficiency of gas injection into low-permeability multilayer hydrocarbon reservoirs

The efficiency of gas injection for developing terrigenous deposits within a multilayer producing object is investigated in this article. According to the results of measurements of the 3D hydrodynamic compositional model, an assessment of the oil recovery factor was made. In the studied conditions, re-injection of the associated gas was found to be the most technologically efficient working agent. The factors contributing to the inefficacy of traditional methods of stimulating oil production such as multistage hydraulic fracturing when used to develop low-permeability reservoirs have been analyzed. The factors contributing to the inefficiency of traditional oil-production stimulation methods, such as multistage hydraulic fracturing, have been analysed when they are applied to low-permeability reservoirs. The use of a gas of various compositions is found to be more effective as a working agent for reservoirs with permeability less than 0.005 µm2. Ultimately, the selection of an agent for injection into the reservoir should be driven by the criteria that allow assessing the applicability of the method under specific geological and physical conditions. In multilayer production objects, gas injection efficiency is influenced by a number of factors, in addition to displacement, including the ratio of gas volumes, the degree to which pressure is maintained in each reservoir, as well as how the well is operated. With the increase in production rate from 60 to 90 m3 / day during the re-injection of produced hydrocarbon gas, this study found that the oil recovery factor increased from 0.190 to 0.229. The further increase in flow rate to 150 m3 / day, however, led to a faster gas breakthrough, a decrease in the amount of oil produced, and a decrease in the oil recovery factor to 0.19 Based on the results of the research, methods for stimulating the formation of low-permeability reservoirs were ranked based on their efficacy.

Non-Stationary Flooding Based on Application of a Thermoactive Polymer Composition at Offshore Fields

A high performance technology has been developed for unstable waterflooding of layered-heterogeneous producing reservoirs of oil fields with a thermal gradient. The technology is based on cyclic injection of a thermoactive low-viscosity oil-soluble liquid polymer composition into the formation, which passes into a high-viscosity phase in situ, blocking the produced formation water flow. Application of the technology results in the increase of area of stimulation, both along the strike and vertical sweep efficiency. Monitoring the reservoir filtration characteristics enables control of the profile of the mixture advance in the formation. The effect of unstable injection of the proposed thermoactive polymer composition on the residual resistance factor was studied in an experimental setup consisting of two parallel-connected linear reservoir models with different permeability. The composition contains a working agent, a dispersant and sea water. The optimal ratio of the components that make up the composite mixture was determined as a result of laboratory and experimental studies. The viscosity behavior of the composite mixture at different temperature values for reservoir conditions is determined. Monitoring techniques for reservoir filtration properties have been developed in order to control the flow profile of the mixture in the reservoir. The analysis of the obtained results showed the efficiency of this technology for layered-heterogeneous reservoirs with a thermal gradient and the availability of overflows. This technology enables aligning area of stimulation, both along the horizontal and vertically using smaller volumes of the agent and with a slight change in the injection pressure. Unstable injection of the composite system provides a significant additional removal of residual oil. Thermoactive polymer composition should be injected cyclically in order to increase the reservoir coverage, align the frontal advance and for enhanced oil recovery due to the involvement of low-permeability oil-saturated areas into the development. This method allows you to change the direction, flow rates, and create unsteady cyclic pressures. A redistribution of formation fluids, a decrease in capillary pressures and the flow of a working agent into oil-saturated low-permeability zones occurs under the positive and negative pressure drops in the formation. The proposed technology was implemented in the section V of the block of the «Neft Dashlary» field (X horizon) in April-June 2016 and in the section of the «Pirallahi» field (KSw) in February-March 2017. At the pilot site of the «Neft Dashlary» field, the impact effect continued until May 1, 2017. Additional oil production in the period from 01.05.2016 to 01.05.2017 made up 3201.4 tons. Additional oil production at the selected area of the Pirallahi field by the end of 2017 made up 170 tons.

SUCCESSFUL APPLICATION AND LIMITATIONS OF HORIZONTAL WELLS

In fields with low-permeable reservoirs, the use of vertical wells becomes economically unprofitable, since a significant amount of reserves remains not involved in development. In these conditions, the most rational use of horizontal wells becomes. A horizontal well is drilled parallel to the plane of the reservoir and can drain a larger area than a vertical one, which makes it possible to increase the impact of the working agent. This, in turn, leads to an increase in well productivity and, ultimately, to an increase in oil recovery of productive formations. Due to the horizontal wellbore, fractured areas are exposed, due to which the flow rates of these wells increase somewhat compared to vertical ones. It becomes possible to develop a reservoir with minimal drawdowns with a much smaller number of wells. The purpose of this article is to provide a brief overview of the field application of horizontal wells in various reservoir conditions. The review of economically successful and unsuccessful wells allows the creation of a certain kind of list of parameters that are of the greatest importance for consideration in order to select a commercially successful application of horizontal wells.

EFFICIENCY OF USING HEAT PUMPS IN AIR CONDITIONING SYSTEMS

This article discusses the relevance of the use of heat pumps in air conditioning systems. The features of the use of passive and active air conditioning schemes with the use of heat pumps are considered. The object of the study is the SCR of an administrative building in the basic configuration and with the use of a heat pump. For a comparative assessment of the energy efficiency of the SCR, a preliminary study was carried out on the choice of the working agent of the heat pump. The paper shows the technical and economic importance of using these circuit solutions for SCR from the point of view of solving energy saving issues and ensuring the safe operation of the system as a whole.

ABOUT THE POSSIBILITY OF APPLICATION OF ORD TECHNOLOGY IN MULTI-LAYER DEPOSITS IN THE DESIGN OF STAGE III DEVELOPMENT

This article discusses the possibilities of using the Simultaneous Separate Injection technology of the working agent in multi-layer fields in order to improve oil recovery, energy state of the reservoir and economic stability in the design of the third stage of the field development.

Comparative study of the operational properties of deviated and straight gas-lift wells and sensitivity analysis of pressure gradient

The article presents a benchmarking analysis of the complex well body structure effect on the hydraulic parameters of the liquid-gas flow pattern in deviated wells. The difference between the consumption of the working agent (gas) required to lift the same amount of liquid from the same depth in vertical and inclined gas-lift wells is shown. Considering the complexity of the hydrodynamic flow properties in deviated wells, the impossibility of analytical flow simulation, the article provides the problem study using statistical methods and gives its practical solution. The article presents a mathematical expression to determine the dynamic pressure gradient using this method, that is, by group calculation of indicators of gas-lift wells with an deviated body, and its numerical value was found.

Study the effect of nitrogen gas on phase behavior of gas condensate systems and dispersion of retrograde condensate

The effect of nitrogen gas on the phase transformation of gas condensate systems and its efficiency as a «working agent» for the production of precipitated retrograde condensate has been analyzed. Experimental studies on the pVT bomb based on a special methodology have clarified some contradictions that still exist in this area. Thus, the physical-thermodynamic nature of the different ways effect of nitrogen gas on the retrograde condensation pressure of the formation system or the stability of its dispersed state depending on the temperature range is explained. The research surveys are also studied the effect of nitrogen gas on gas phase dispersion in the precipitated retrograde condensate and liquid-gas interfacial exchange processes under different thermo-baric conditions. It was defined that if nitrogen gas is used to develop the wellbore zone of a gas condensate well, its efficiency should be specified depending on the degree of wellbore saturation with retrograde condensate, the amount of nitrogen in the working agent, formation temperature and number of cycles affecting the wellbore.

Research of Gas Jet Pumps with Diagraphic, Conical and Laval Nozzles

This article is devoted to the research of the nozzle type (conical, diaphragm and Laval nozzles) influence on the characteristics of the jet pumps, in which high-pressure gas is used as a working agent for ejecting gas and liquid. The scheme of the test bench, the working characteristics of the jet pumps and the results of the experiment are also described in detail. The article provides recommendations on the most optimal configurations for different nozzles and experimentally proved the effectiveness of conical nozzles in both pressure and energy characteristics.