Oleksandr Burachok

CO2 emissions are considered to be the main contributor to global warming and climate change. One of the ways reducing the emissions to atmosphere is a proper capture and further geological storage of the carbon dioxide.
In the oil industry, CO2 is used as one of the injection agents to displace oil and enhance its recovery. Due to the low multi-contact miscibility pressure between CO2 and hydrocarbons, fully miscible condition is quickly reached, leading to efficient displacement and high… Mehr anzeigen

CO2 emissions are considered to be the main contributor to global warming and climate change. One of the ways reducing the emissions to atmosphere is a proper capture and further geological storage of the carbon dioxide.
In the oil industry, CO2 is used as one of the injection agents to displace oil and enhance its recovery. Due to the low multi-contact miscibility pressure between CO2 and hydrocarbons, fully miscible condition is quickly reached, leading to efficient displacement and high recovery factors. The utilization of the depleted gas fields for CO2 storage, however, is considered as the option that is more expensive compared to oil field, since the enhanced recovery of gas with CO2 is not effective. For this reason, our study considers the potential use of CO2 EOR in depleted gas-condensate fields. This potential is evaluated by performing numerical simulations for the typical-size gas-condensate reservoirs with no active aquifer, in order to estimate both the storage efficiency and the additional oil recovery from condensed C5+ hydrocarbon fractions, that otherwise will be never recovered and lost in the
reservoir. Obtained results indicate significant potential for CO2 storage and additional condensate recovery from the typical gas-condensate field of Eastern Ukraine. Weniger anzeigen

A well-established method for fluid characterization is to use regression on the critical parameters of the grouped components of an equation of state (EOS) to replicate the results of fluid experiments performed in the laboratory, mainly constant composition expansion (CCE), constant volume depletion (CVD), and differential liberation (DL). In the case of many mature reservoirs, however, proper fluid laboratory examination is not available. This paper proposes an alternative fluid… Mehr anzeigen

A well-established method for fluid characterization is to use regression on the critical parameters of the grouped components of an equation of state (EOS) to replicate the results of fluid experiments performed in the laboratory, mainly constant composition expansion (CCE), constant volume depletion (CVD), and differential liberation (DL). In the case of many mature reservoirs, however, proper fluid laboratory examination is not available. This paper proposes an alternative fluid characterization methodology based on the Engler distillation test (ASTM86). Its objective is to help engineers derive key fluid parameters such as formation volume factors and oil-gas ratios in the absence or limitation of PVT-cell experimental data, based only on the Engler distillation test (ASTM86) results and a fluid composition up to C5+.
The suggested methodology was applied on multiple highly heterogeneous fields located in the Dnieper-Donetsk Basin in Eastern Ukraine and proved to be useful for all the fields of varying fluid types ranging from lean gas with a condensate yield (presence of C5+ per cubic meter of gas) of 10 g/m3 to very rich retrograde gases of 500 g/m3. Weniger anzeigen

Commonly, chemical enhanced oil recovery (CEOR) methods are evaluated for and applied in oil reservoirs whereas gas recycling with methane or nonhydrocarbon gases is considered a primary method to improve the recovery of liquid hydrocarbons from gas-condensate reservoirs. Gas cycling works well and provides high recoveries when implemented at the early stage when reservoir pressure is kept close to the dewpoint. However, gas cycling has several downsides. During the recycling stage, additional… Mehr anzeigen

Commonly, chemical enhanced oil recovery (CEOR) methods are evaluated for and applied in oil reservoirs whereas gas recycling with methane or nonhydrocarbon gases is considered a primary method to improve the recovery of liquid hydrocarbons from gas-condensate reservoirs. Gas cycling works well and provides high recoveries when implemented at the early stage when reservoir pressure is kept close to the dewpoint. However, gas cycling has several downsides. During the recycling stage, additional gas must be provided to compensate for extracted volumes of natural gas liquids. In addition, when nitrogen is used, after it breaks through to the production well, that well should be re-equipped for injection, and an additional production well must be drilled. If reservoir pressure is significantly reduced below the dewpoint and in-situ condensation takes place, gas recycling will require enormous volumes of gas to increase the pressure and initiate retrograde vaporization. To recover condensed hydrocarbons, in this study, we evaluated the possibility of applying different chemical agents, such as surfactants, alkalis, polymers, and their combination, for their displacement and revaporization. Each technology was optimized and compared based on economic and technical indicators. Previously, we studied the possibility of CEOR optimization under geological uncertainties, but due to applied constraints and presence of geological uncertainties introduced through multiple model realizations, it was not possible to make a clear conclusion on the best technology.
The results of the work showed that chemical agents could be successfully applied to recover condensed liquids from depleted gas-condensate reservoirs and increase total hydrocarbon recovery.
Presented results could be used as a guidance for selection of possible CEOR methods during optimization of condensate recovery from depleted fields. Weniger anzeigen

Traditional fluid phase behavior characterization approach relies on creation of the equation of state (EOS) based on initial composition of reservoir fluid and its future regression for critical parameters (pressure and temperature), binary interaction coefficients, acentric factors of residual “plus” fraction or pseudo-components. The adjustment is done until the moment when EOS is reproducing the results of laboratory experiments. Classic PVT experiments performed on gas-condensates and… Mehr anzeigen

Traditional fluid phase behavior characterization approach relies on creation of the equation of state (EOS) based on initial composition of reservoir fluid and its future regression for critical parameters (pressure and temperature), binary interaction coefficients, acentric factors of residual “plus” fraction or pseudo-components. The adjustment is done until the moment when EOS is reproducing the results of laboratory experiments. Classic PVT experiments performed on gas-condensates and volatile oils are constant composition expansion (CCE), constant volume depletion (CVD) and separator tests. However, in the case of most Ukrainian fields, discovered and explored in the last century, not only the reliable detailed initial fluid composition is not available, but phase behavior was studied with non-equilibrium method of so-called differential condensation, that does not allow their direct application for PVT models creation. Due to significant uncertainty in input data, particularly a) condensate production allocation; b) commingled production from multiple reservoirs with different C5+ yield; c) non-recorded change of separator conditions that affects liquid extraction and its density; d) technological production losses, issues of reproducing the condensate production during history matching of several models of Dniper-Donetsk Basin were faced. There was proposed and explained in detail an example of single-cell reservoir simulation model application concept for quality check of created PVT model for one of the fields with potential yield of 86 g/m3. The idea of the concept is based on the reproduction of material balance of gas-condensate reservoir through one conditional well controlled on a primary (gas) phase, that allows quick identification of changes into calculated gas-condensate yield curve, necessary for matching of condensate production. Implementation of these changes allows quick and precise full-field model calibration. Weniger anzeigen

Traditionally, deep saline aquifers are considered and evaluated for long term geological storage of CO2 due to relatively high CO2 solubility in water. In the oil industry, also, CO2 is used is as one of the injection agents to displace oil and enhance its recovery. The utilization of depleted gas fields for CO2 storage, however, is considered to be a more expensive option compared to oil field, since the enhanced recovery of gas with CO2 is not effective. For this reason, our study considers… Mehr anzeigen

Traditionally, deep saline aquifers are considered and evaluated for long term geological storage of CO2 due to relatively high CO2 solubility in water. In the oil industry, also, CO2 is used is as one of the injection agents to displace oil and enhance its recovery. The utilization of depleted gas fields for CO2 storage, however, is considered to be a more expensive option compared to oil field, since the enhanced recovery of gas with CO2 is not effective. For this reason, our study considers the potential use of CO2 EOR (enhanced oil recovery) in depleted gascondensate fields.
This potential is evaluated by performing numerical simulations for typical-size gas-condensate reservoirs with and without active aquifers, in order to estimate both storage efficiency and additional oil recovery from condensed C5+ hydrocarbon fractions, that otherwise will be never recovered and lost in the reservoir. Obtained results indicate significant potential for CO2 storage and additional condensate recovery from the typical gas-condensate field of Eastern Ukraine. Weniger anzeigen

Досліджено умови за яких може бути досягнуто повне змішування азоту і вуглекислого газу із типовими газоконденсатними пластовими флюїдами із потенційним вмістом рідких вуглеводнів 100, 300 і 500 г/м3. За умови суттєвого виснаження пластової енергії і низьких пластових тисків, що характеризує кінцеві стадії розробки родовищ, повне змішування неможливо досягнути для жодного з цих невуглеводневих газів. Використання вуглекислого газу є більш сприятливим, оскільки на ранніх стадіях розробки… Mehr anzeigen

Досліджено умови за яких може бути досягнуто повне змішування азоту і вуглекислого газу із типовими газоконденсатними пластовими флюїдами із потенційним вмістом рідких вуглеводнів 100, 300 і 500 г/м3. За умови суттєвого виснаження пластової енергії і низьких пластових тисків, що характеризує кінцеві стадії розробки родовищ, повне змішування неможливо досягнути для жодного з цих невуглеводневих газів. Використання вуглекислого газу є більш сприятливим, оскільки на ранніх стадіях розробки, дозволяє отримати повне багатоконтактне змішування за тисків нижчих за початковий пластовий тиск. Проаналізовано ефективність нагнітання азоту і вуглекислого газу для витіснення конденсату, що випав у пласті, за умови максимального виснаження пластової енергії, коли пластовий тиск рівний тиску максимальної конденсації. Використання вуглекислого газу дозволяє збільшити коефіцієнт конденсатовилучення на 7%, у порівнянні з азотом для пластових систем із високим потенційним вмістом конденсату (500 г/м3). Weniger anzeigen

Виконано аналіз стану та результатів наукових досліджень із проблем конденсатовилучення з родовищ вуглеводнів на різних стадіях їх розробки. Проаналізовано напрямки досліджень проблем підвищення конденсатовилучення, що проводяться в Україні. Розглянуто основні технології підвищення конденсатовилучення, а саме нагнітання: сухого газу, азоту, вуглекислого газу, вуглеводневих розчинників, поперемінне води і газу, хімічних агентів. Виконано порівняння ефективності між різними методами. Узагальнено… Mehr anzeigen

Виконано аналіз стану та результатів наукових досліджень із проблем конденсатовилучення з родовищ вуглеводнів на різних стадіях їх розробки. Проаналізовано напрямки досліджень проблем підвищення конденсатовилучення, що проводяться в Україні. Розглянуто основні технології підвищення конденсатовилучення, а саме нагнітання: сухого газу, азоту, вуглекислого газу, вуглеводневих розчинників, поперемінне води і газу, хімічних агентів. Виконано порівняння ефективності між різними методами. Узагальнено результати та подано рекомендації щодо використання того чи іншого методу. Weniger anzeigen

Western Ukraine as well as Crimea Peninsula is well known for their geothermal potential. The classic low enthalpy geothermal project is based on the construction of a binary power plant, and includes recycling of water through one or several doublets of wells; produced hot water is directed to a heat exchanger (vaporizer), in which a secondary (working) fluid with low boiling point and high vapor pressure vaporizes and rotates a turbine to produce electricity. The highest risk for the project… Mehr anzeigen

Western Ukraine as well as Crimea Peninsula is well known for their geothermal potential. The classic low enthalpy geothermal project is based on the construction of a binary power plant, and includes recycling of water through one or several doublets of wells; produced hot water is directed to a heat exchanger (vaporizer), in which a secondary (working) fluid with low boiling point and high vapor pressure vaporizes and rotates a turbine to produce electricity. The highest risk for the project is associated with drilling new wells, which may not hit the target or not have the required productivity. Western Ukraine is one of the oldest oil and gas production regions in Europe. The majority of the fields are on a late stage of the development that is characterized with high produced volumes of water that after separation is being reinjected back for pressure support. In this study, we evaluated the possibility of geothermal energy production, extracted from water that is produced together with oil and gas, based on numerical reservoir simulation models for a typical reservoir setting. Weniger anzeigen

Most of the fields in the Basin of the current study are represented by multi-stacked thin reservoirs with total thickness up to 2 thousand meters containing oil, gas-condensate and dry gas with high lateral and vertical heterogeneity. The asset in this study is a mature gas field with more than 50 years of production history, that consists from 15 gas-bearing sands of variable gas composition, that are in commingled production through the slotted liner completions while some of the sands are… Mehr anzeigen

Most of the fields in the Basin of the current study are represented by multi-stacked thin reservoirs with total thickness up to 2 thousand meters containing oil, gas-condensate and dry gas with high lateral and vertical heterogeneity. The asset in this study is a mature gas field with more than 50 years of production history, that consists from 15 gas-bearing sands of variable gas composition, that are in commingled production through the slotted liner completions while some of the sands are not yet under development and therefore, shouldn’t be considered in history matching and excluded from material balance P10 reserves calculation but rather in P50 and P90 resources. This paper shows how the application of stochastic approach for facies modeling followed by petrophysical porosity, in the presence of non-resolutive 3D seismic could help to guide the property distribution and evaluate geological uncertainties. The next very important step in the applied workflow was flow-based ranking and selection of representative case based on connected (drained) volumes that helps to achieve history match for selected base case in the presence of additional high uncertainty in contact levels and quality of production data. Weniger anzeigen

Unlike other renewable energy sources, the successful appraisal and development of geothermal heat require an understanding of the subsurface environment. The resource must be identified and quantified to justify the sustainability of the project. Moreover, the acceptability of the geothermal operations must be ensured for the success of the project. Sustainability and acceptability can be addressed with a thorough knowledge of the subsurface. The oil and gas industry has accumulated decades of… Mehr anzeigen

Unlike other renewable energy sources, the successful appraisal and development of geothermal heat require an understanding of the subsurface environment. The resource must be identified and quantified to justify the sustainability of the project. Moreover, the acceptability of the geothermal operations must be ensured for the success of the project. Sustainability and acceptability can be addressed with a thorough knowledge of the subsurface. The oil and gas industry has accumulated decades of experience characterizing deep and ultradeep formations, including in the challenging conditions that are commonly found in geothermal sites (high temperature, pressure, salinity, corrosion…). This experience has already been successfully applied to develop and apply solutions to explore, map, and produce geothermal resources (Sosio et al., 2019). Subsurface modelling, in particular, enables the quantifying of performance and risks associated with development and operations. This paper presents a case study of the application of 3D modelling of a geothermal site in eastern France. An integrated geological, thermohydraulic, and geomechanical description of the subsurface is applied to the data typically available for low-to-medium-enthalpy geothermal reservoirs in sedimentary basins. We show how this description is used to evaluate the performance and risk factors related to the development and operation of the geothermal site, potentially improving its economic and social aspects. Weniger anzeigen

In oil and gas exploration and appraisal projects, correct estimation of initial resources and reserves is one of the key elements for development feasibility selection and the "green light". Historically, this decision has been purely based on probabilistic determination of hydrocarbons in place derived from the response of the static geomodels on stochastically varied key uncertainty parameters. Selected models that represent P10, P50 and P90 cases were later used for recovery forecasting… Mehr anzeigen

In oil and gas exploration and appraisal projects, correct estimation of initial resources and reserves is one of the key elements for development feasibility selection and the "green light". Historically, this decision has been purely based on probabilistic determination of hydrocarbons in place derived from the response of the static geomodels on stochastically varied key uncertainty parameters. Selected models that represent P10, P50 and P90 cases were later used for recovery forecasting, which, in most cases, do not represent the corresponding probabilistic recovery estimates. By applying streamline flow simulation during uncertainty analysis, we are able to estimate connected pore volumes that are coupled with static volume calculations, which enables selecting representative models that fulfill both static and dynamic requirements. In this paper, we present a unique workflow that eliminates the gap between static volumetric and flow-based approaches for ranking and selection of representative geological models. Weniger anzeigen

Drilling success forecast from reservoir modeling is based on the quality and availability of input data. Analysis and correlation of wellbore and 3D seismic data applied to geothermal reservoir modeling help to mitigate project risks. The extraction and application of geomechanic data maximize geological information to optimize well path planning and to identify preferred drilling targets in areas of faults and permeable reservoir zones. Pore content, porosity and permeability are in… Mehr anzeigen

Drilling success forecast from reservoir modeling is based on the quality and availability of input data. Analysis and correlation of wellbore and 3D seismic data applied to geothermal reservoir modeling help to mitigate project risks. The extraction and application of geomechanic data maximize geological information to optimize well path planning and to identify preferred drilling targets in areas of faults and permeable reservoir zones. Pore content, porosity and permeability are in correlation to geomechanical information from the seismic velocities vp and vs. This article shows a method for the detection of increased permeability zones based on extraction of geomechanical information from sonic wellbore and seismic cube data. Weniger anzeigen

The possibility of gas-condensate pool’s flooding as one of the methods for laid-down condensate recovery is researched in this paper. There have been given the results of development processes’ computer modeling for several variants, the influence of relative permeabilities on final oil recovery is researched. There have been given the recommendations for practical application of gas-condensate pools flooding based on obtained results.

Most of the Ukrainian oil fields is on the final stage of the development. At this stage high drop of reservoir pressure and termination of filtration from low permeability areas take place. Drilling of well cluster is one of proposed methods of oil recovery from such areas. The main problem of rational usage of this method is correct determination of rational number of horizontal wells (rays), length of horizontal parts and radius of reservoir entry (remoteness from the main vertical part of… Mehr anzeigen

Most of the Ukrainian oil fields is on the final stage of the development. At this stage high drop of reservoir pressure and termination of filtration from low permeability areas take place. Drilling of well cluster is one of proposed methods of oil recovery from such areas. The main problem of rational usage of this method is correct determination of rational number of horizontal wells (rays), length of horizontal parts and radius of reservoir entry (remoteness from the main vertical part of the cluster). It is advisable to apply this scheme on new fields too. For example instead of drilling vertical wells to drill 3–4 clusters of horizontal wells. The problem of hydrodynamic horizontal wells interference will arise any way. These problems are solved in this paper. Weniger anzeigen

During the projecting of gas-condensate fields (GCF) development the main attention is paid to maximum extraction of propane-butane fractions. In most of GCF the initial reservoir pressure is greater than the condensing pressure, therefore from the beginning their development is designed on depletion regime. The consecutive drop of reservoir pressure take place during the development process. The pressure gradient is necessary condition for fluid filtration, therefore first the pressure drops… Mehr anzeigen

During the projecting of gas-condensate fields (GCF) development the main attention is paid to maximum extraction of propane-butane fractions. In most of GCF the initial reservoir pressure is greater than the condensing pressure, therefore from the beginning their development is designed on depletion regime. The consecutive drop of reservoir pressure take place during the development process. The pressure gradient is necessary condition for fluid filtration, therefore first the pressure drops to condensation value within the depression cone near around production wells. Thus, an additional phase is appearing. The neglect of additional phase appearance during the projection of the development indexes usually take place. Only one phase (gas) or two phases (gas and water) are usually taking into consideration. Creation of new mathematical model for consideration of condensate phase in the flow is given in this paper. The system of two differential equations for description of gas-condensate mixture filtration in the reservoir was proposed by Pykhachov and Isaev [2]. The equations were obtained based on Darcy’s law of filtration and equation of continuity. This model doesn’t consider actual phase transition during the pressure change and admits constancy of fluid properties in time. The model presented in this paper is based on principles for calculation of non-isothermal and isothermal filtration of gas in porous medium within the presence of water. The author proposed to replace water by condensed gas. For simplification of the model only two phases (gas and condensate) are observed, without presence of water. Weniger anzeigen