Laboratory Studies of Carboniferous Reservoirs of High-Viscosity Oil Fields Using Carbondioxide

It is of current concern for the Permian-Carboniferous reservior of the Usinskoye field to develop low-permeable matrix blocks of carboniferous reservoirs, which contain major reserves of high-viscosity oil. To increase effectiveness of the currently used thermal oil recovery methods, the authors suggest using carbon dioxide as a reservoir stimulation agent. Due to a high mobility in its supercritical condition, СО2 is, theoretically, able to penetrate matrix blocks, dissolve in oil and, additionally, decrease its viscosity. Thus, СО2 applications together with a heat carrier could increase effectiveness of the high-viscosity oil recoveries and improve production parameters of the Permian-Carboniferous reservior of the Usinskoye field. During carbon dioxide injections, including combinations with various agents, some additional oil production is possible due to certain factors. Determination of the influencing factors and detection of the most critical ones is possible in laboratory tests. So, laboratory studies entail the key stage in justification of the technology effectiveness. The paper deals with describing the laboratory facilities and methodologies based on reviews of the best world practice and previous laboratory researches. These aim at evaluating effectiveness of thermal, gas and combined oil recovery enhancement methods. In particular, the authors explore experimental facilities and propose methodology to perform integrated researches of the combined heat carrier and carbon dioxide injection technology to justify the effective super-viscous oil recovery method.

Prediction of Oil and Gas Occurrence in the Southern Part of Perm Krai Based on Regional 3D Modeling

The territory of the southern part of Perm Krai is well studied in terms of oil and gas prospecting. About 150 oil and gas fields have been discovered there, over 7000 deep wells have been drilled, and 3D seismic surveys have been completed on the area exceeding 5000 km2. The state of exploration of the territory allows us to have an immense array of geologic information, which can be used to search and predict oil and gas occurrence in structures that remain left out or that have not been studied yet. The research area was limited by the confines of Perm Krai in the south, west, and east and by a conventional line in the north along the boundary of the completed seismic surveys. To study the territory based on the reflecting horizon surface of Perm Krai, a 3D geological model has been built within IRAPRMS software system. The model calculates a regional, a zonal and local constituents of the reflecting horizon of Perm Krai. The local constituent allowed us to single out structures divided into three categories: structures of ascertained oil and gas occurrence, structures that do not contain oil and gas (empty), and structures for which a prediction is needed. In the model, structural parameters representing a trap potential for the accumulation and retention of hydrocarbons were calculated. Moreover, geochemical parameters showing a generation potential and a migration constituent, as well as hydrogeological parameters as indirect data to determine the saturation of structures with hydrocarbons, were downloaded into the model. The obtained data about the importance of each parameter for all structures allowed us to generate a single database and predict oil and gas occurrence by the machine learning method, i.e. through the step-bystep linear discriminant analysis. Based on the results of the linear discriminant analysis, 138 predicted structures were arranged in groups in accordance with degrees of their potential. By applying the built individual probability models, a map of the regional probability of structures’ saturation with hydrocarbons was obtained; this map served as a basis and amendment of oil and gas geological zoning boundaries of the southern part of Perm Krai.

Alteration of Physical and Chemical Properties of Clays Subjected to Pressure

Clays represent complex polymineral formations. The properties of clays, including sorption, are largely determined by the structure of their crystal lattice, mineral composition and particle size distribution, as well as by environmental conditions. The mineral composition of clays is represented by the energy on the surface of particles; and the particle size distribution is represented by the active surface area of particles. These two complex parameters mainly determine the sorption activity of clays. To change the sorption activity of clays, the latter are subjected to mechanical treatments, thermal modifications, and chemical activations with the use of chemical agents such as acids, alkalis, salts at various exposure times. Therefore, a study of patterns of changes in the structure and sorption properties of clays subjected to pressure was conducted. Experimental studies have shown that if kaolin is subjected to pressure, defects are formed in the structural pack of kaolinite mineral due to the removal of Al3+, Fe3+/2+, Mg2+, Si4+ ions from it. In this case, pressure has the maximum influence on the removal of Al3+ ions from the pack. As a result of the removal of ions, the formation of the defects deforms the crystal lattice of kaolinite. Data obtained through IR spectroscopy confirm the increase of defectiveness (irregularity) of the structure of kaolinite. It has been revealed that when kaolin is subjected to a pressure of 0–150 MPa, the sorption activity mostly depends on рН of the diffuse layer particle solution ZрН = 73 % and crystallite defectiveness degree ZМк = 24 %. The specific surface area of particles ZSsa = 1 % and kaolinite pack defectiveness Zс = 2 % do not have any significant influence on sorption. If kaolin is subjected to a pressure of 150–800 MPa, kaolin sorption activity mostly depends on kaolinite pack defectiveness Zс = 74 % and crystallite pack defectiveness ZМк = 19 %. The specific surface area of particles ZSsa = 3 % and рН of the diffuse layer particle solution ZрН =4 % do not have any significant influence on sorption.

Estimating the Potential of Unmanned Aerial Vehicle Use in the Oil and Gas Industry

The relevance of the study is explained by the need to use unmanned aerial vehicles (UAV) to serve engineering and geodetic tasks in the oil and gas industry. Airborne photographic survey using unmanned aerial vehicles is currently an advanced technology in the area of geodesy and it replaces such methods as tacheometry, satellite-based positioning in RTK modes, manned aerial photography, and aiborne laser scanning (ALS). The potential for using UAVs in the oil and gas industry today is truly enormous. Numerous safety and reliability problems, which traditionally have been cost consuming for oil and gas companies, can be effectively addressed using UAVs. The study included processing of data obtained from the unmanned complex in three modern software packages (Agisoft Photoscan Professional, v 1.2.5.2594 (Russia), ERDAS IMAGINE, v 2015 (USA) and Pix4Dmapper Pro (Switzerland)) of various automation degrees; assessment of accuracy in ArcMap software by superimposing a topographic plan on an orthomosaic with a scale of 1: 500 on the territory under consideration; calculation of economic and labor costs. As part of the study, it was proved that the use of UAVs was possible not only for the geodetic work, but also for solving other equally important tasks of the oil and gas industry, which leads to a decrease in economic and environmental risks, automation of processes related to monitoring of oil facilities, prevention of illegal attempts of pipeline tie-ins, oil spills. In addition, based on the obtained orthophotomaps, the economic, accuracy and labor-time feasibility of using unmanned systems were confirmed. It has been established that the use of unmanned aerial vehicles in various fields of oil and gas activities for solving engineering and geodetic problems is an integral part of any company engaged in the production and transportation of hydrocarbons.

Assessing the Impact of Uncertainty Parameters on Forcasting Production Parameters

At the stage of developing a geological and hydrodynamic reservoir model, uncertainties in input data may lead to errors in simulation results and subsequent inaccurate economic evaluations of oil or gas field potentials. In order to improve predictive reliability, a study was completed to assess how input data of a hydrodynamic model influence forecasts of main parameters of a production using the example of the Tournaisian site of the Soldatovskoye field. The study presents an approximate algorithm reducing uncertainties and improving the forecast reliability of the production parameters obtained using a geological and hydrodynamic reservoir model. The algorithm includes a substantiated selection of the initial sensitivity parameters, an evaluation of the impact of the initial parameters on the hydrodynamic reservoir model using the sensitivity analysis, as well as a selection of an optimal range of variations of the uncertainty parameters as a result of the multivariant hydrodynamic simulation adaptation, calculation and analysis of the multivariant hydrodynamic reservoir model forecast. The study aims to clarify the design process parameters of the development, assess the risks of non-confirmation of the hydrodynamic simulation forecasting, and make recommendations and proposals to study those uncertainty parameters, which influence most on certain predicted production parameters of an asset. As a result, a block diagram of the approach is presented in order to generalize and replicate it on potential and important oil and gas fields. The described approach of the model adaptation and calculations of the predicted options in conditions of uncertainty of the initial model parameters make it possible to obtain a more accurate and less arbitrary hydrodynamic reservoir model, which reduces probability of an incorrect evaluation of potentials of a young field or a field at an early production stage.

Application of Integrated Modeling in the Oil and Gas Industry

The present stage of the oil industry development is characterized by a growing share of hard to reach reserves, the amount of complicated well stock, oil production costs and increasing requirements to production accounting accuracy, implementation of energy-efficient and resource-efficient technologies for development and production, in conditions of the multifactorial evaluation of asset development prospects a problem of the asset intellectualization is a priority. Within this problem, automation and implementation of integrated approaches to production optimization, prevention and control of difficulties, effective asset development management both on operative and long-term levels are considered. At present, a complex and effective tool in resolving the problem is an integrated model, i.e. a model of a well production process (oil, gas, water), including all production chain elements in the form of consequential component models. An integrated simulation is effectively used in operational activities of LUKOIL-PERM LLC and is an optimal tool to solve multidisciplinary tasks in field development and technology of oil and gas production, transportation and processing (using software by Petroleum Experts company). Experience of implementing the integrated simulations suggests a synergetic effect related to a need in developing associated aspects manifesting themselves by improvement of skills of the specialists, improvement of input data quality and increase of input data volume, improvement of separate component quality during their integration. A set of actions developed and substantiated using the integrated simulations and their separate components resulted in obtaining some additional oil production over 21.9 thou. t.

The Influence of Lithologic and Facies Zones on the Efficiency of Cyclic Steam Simulation (as Illustrated by the Permian–Carboniferous Reservoir of Super Viscous Oil of the Usinskoye Oil Field in the Komi Republic)

The influence of lithologic facies zones on the development of the Permian-Carboniferous reservoir of the Usinskoye oil field was evaluated. To meet the objective, reservoir porosity and permeability of each lithologic facies zone were addressed, the facial zoning influence on the rate of oil extraction in the Permian-Carboniferous reservoir of the Usinskoye oil field was analyzed, and the performance was evaluated after cyclic steam injection. The research deals with the Permian-Carboniferous reservoir of the Usinskoye oil field in the Komi Republic. In accordance with a developed format, a database of core analysis results and a base on cyclic steam simulation efficiency for the period of 5 years were collected. To determine the belonging of facies, we used the classification system for carbonate rocks suggested by Robert J. Dunham with the additions proposed by A.F. Embry and J.E. Klovan (based on the prevalence of structure components in limestone, the grouting agent type, as well as their interrelation in the rock). Based on the material composition of the rock and on the structural parameter, the following three main facies zones were identified: shallow-water carbonates (internal ramp zone), organogenic buildup (middle ramp zone), shallow-water offshore plain (middle ramp zone, external ramp zone in part). In addition, among the facies, it is possible to single out a moderately deep-water offshore plain (external ramp zone). In accordance with the research results, curves of the displacement coefficient distribution related to porosity were obtained and guidelines on determining the priority drilling sites within the area were given. As per the core analysis results, in the eastern part of the field, a zone of organogenic buildups was clearly determined; such buildups were formed mainly in the middle and late Carboniferous Period and Early Permian period. In the north-western part of the field, the existence of an internal ramp with shallow-water carbonate facies was assumed. The location of the priority drilling wells was chosen with regard to the fact that each cluster of development drilling wells is to penetrate facies of organogenic buildups having the best reservoir properties and oil displacement efficiency.

Refining Permeability Values for History-Matching of the Reservoir Simulation Model

Reservoir simulation models are used to design oil field developments, estimate efficiency of geological and engineering operations and perform prediction calculations of long-term development performances. A method has been developed to adjust the permeability cube values during reservoir model history-matching subject to the corederived dependence between rock petrophysical properties. The method was implemented using an example of the Bobrikovian formation (terrigenous reservoir) deposit of a field in the Solikamskian depression. A statistical analysis of the Bobrikovian formation porosity and permeability properties was conducted following the well logging results interpretation and reservoir modelling data. We analysed differences between the initial permeability obtained after upscaling the geological model and permeability obtained after the reservoir model history-matching. The analysis revealed divergences between the statistical characteristics of the permeability values based on the well logging data interpretation and the reservoir model, as well as substantial differences between the adjusted and initial permeability cubes. It was established that the initial permeability was significantly modified by manual adjustments in the process of history-matching. Extreme permeability values were defined and corrected based on the core-derived petrophysical dependence KPR = f(KP) , subject to ranges of porosity and permeability ratios. By using the modified permeability cube, calculations were performed to reproduce the formation production history. According to the calculation results, we achieved convergence with the actual data, while deviations were in line with the accuracy requirements to the model history-matching. Thus, this method of the permeability cube adjustment following the manual history-matching will save from the gross overestimation or underestimation of permeability in reservoir model cells.

Analysis of Petrophysical Studies of Deep Oil and Gas Reservoirs of Onshore and Offshore Fields in Azerbaijan

The paper presents results of generalized laboratory studies from an array of petrophysical parameters of reservoir rocks (potential hydrocarbon reservoirs). The study is targeted at well-known horizons of productive strata of the Meso- Cenozoic sedimentary basin. The area under study includes oil and gas onshore and deep offshore fields in Azerbaijan that have been under active continuous developments. The development of these natural hydrocarbon accumulations has over a century-long history, which has shown that the major oil and gas deposits are associated with the South Caspian and Kura depressions subjected to an intensive submersion over the Meso-Cenozoic period. Although many of the fields in these depressions have been exploited for a long time, the commercial potential is high enough, especially in deep-seated areas. Nonetheless, problems associated with extracting oil and gas therefrom are pending final resolutions. Subsoil developments in the region are currently performed at an intensive rate at depths above 4-4.5 km, since most oil and gas deposits have already been explored at shallow and moderate depths (even in hard-to-reach areas). As known in oil industry, the wells with a depth of over 4 km are referred to deep wells, while those with a depth of over 6 km are referred to ultra-deep wells. Moreover, drilling of such wells is associated with serious costrelated challenges. For example, the cost of developing deep and even ultra-deep wells is high enough, ranging from $ 2-3 to $ 9-12 million. This fact emphasizes the need to enhance efficiency of such operations, which requires a highscale geological reasoning of a field’s potential and choice of a good location.

Studying the Wellbore Stability Enhancement Mechanism during Drilling through Fractured Argillites

The paper presents the relevance of enhancing wellbore stability by developing and applying efficient drilling fluid compositions for well constructions in fractured argillite. In the process of well constructions, there comes a range of complications associated with instability of rocks forming borehole walls, which sometimes results in lower penetration rates, higher construction costs and well abandonment. Often, drilling problems occur at drilling through mudrocks that account for up to 70 % of field sections. When using water-base drilling fluids, the mudrock swelling due to the contact with the fluid dispersion medium adversely affects the drilling process and can significantly increase well construction costs. The accumulation of wellbore cavings inhibits well circulation, causes landing of drilling tools and may result in tool sticking. An analysis of drilling problems in fractured argillite is presented; the mechanisms affecting open hole stability in the fractured argillite deposits are shown. The use of potassium chloride is recommended to enhance the stability of argillite-formed borehole walls. The results are supported by experimental studies using the Chenevert method, as well as fracture propping tests. When the argillite sample was placed in potassium chloride (KCl) solution, there was a minor fracture expansion and propagation over the entire sample length, which is a positive result. To enhance wellbore stability, further study approaches are proposed: upgrading mud by adding inhibiting compounds, such as salt solutions in combination with high-molecular polymer compositions.