Open Wells Research Articles

CALCULATION OF THE MAIN ELEMENTS OF THE ROPE-PULLEY DRIVE OF A DOWNHOLE ROD PUMPING UNIT

The goal of minimizing oil production costs is becoming increasingly crucial in current oil production settings, particularly during the operation of oil fields in the final phases of development and the ever-expanding commissioning of difficult-to-recover hydrocarbon reserves. Oil production practice has shown, lengthening the length of the steel pumping plant's loop needs a lower frequency of rolling, which extends the life of the well equipment and enhances pumping installation performance. The engine's weight and cost increase as the drive lengthens. The necessary characteristics made it impossible to build long-stroke balancing drives. One of the ways to solve this problem is the use of long-stroke unbalanced sucker-rod pump drives as part of pumping units, which will significantly reduce energy consumption for oil production and, accordingly, reduce the cost. The presented article shows the prospects of using unbalanced drives of sucker-rod pumping units in the operation of wells by mechanized method. The kinematic-power diagram of the drive of the downhole rod pumping unit is shown. A method for calculating the acting forces is given. To calculate the strength of the structure being developed, it is important to determine the change in the force acting on the suspension point of the rods. In order to carry out repair work, the goal was set to further improve the unbalanced drive WRPU (well rod pump unit). For this, a scheme was proposed for changing the fixed guide pulley to a movable one, installed on the base with the possibility of its rotation. The proposed design of the rotary pulley makes it possible to free up space above the wellhead. Keywords: unbalanced drive, long stroke, swivel pulley, beamless drive of pumping unit, rod suspension point, crank-pulley converting mechanism.

IMPROVING THE CORRECTNESS OF SEPARATE ACCOUNTING OF OIL, ASSOCIATED AND FREE GAS, CONDENSATE AND WATER WHEN CHANGING THE SYSTEM DEVELOPMENT OF OIL AND GAS

The transition to joint development made it possible to significantly increase the current oil production rates due to the breakthrough of free gas, which is the main working agent for bringing borehole fluid to the surface, however, as a result of the operation of wells in this mode, along with a significant increase in oil production rates, an increase in gas production rates was also observed.

Analyses and studies for the selection of the method of dual completion operation of wells in multi-layer fields

Mandatory research and measurement complexes for monitoring development should cover evenly the entire area of the development object, the entire fund of observation wells. They should contain measurements of reservoir pressure for control and piezometric wells, measurements of reservoir and bottom-hole pressures, well flow rates for liquid, gas factors and water content of products for producing wells, measurements of wellhead injection pressures and injection volumes for injection wells, hydrodynamic studies of producing and injection wells in stationary and non-stationary modes, studies on the control of the oil and water contact, gas and oil contact, oil and gas saturation, technical condition of the wellbore by field-geophysical methods, selection and research of deep oil samples, surface rock products of wells (oil, gas, water).
 The paper considers in detail proposals to improve the system of collection, preparation and transport of natural, associated gas and condensate. The topic of operation of gas wells, the state and proposals for improving the system of gas and condensate collection and treatment, requirements for structures, drilling technology, the method of reservoir opening and well development on the example of the Altyguyi gas condensate field is touched upon. The choice and justification of the well design in accordance with the intervals of compatibility of the well section according to mining and geological drilling conditions based on the forecast curves of reservoir pressures and rock rupture pressures (combined pressure graph), as well as methods of primary and secondary opening of productive formations and their development are considered in detail.

DEVELOPMENT OF TECHNOLOGY FOR CLEANING THE BOTTOM-HOLE ZONE OF THE FORMATION FROM ASPHALT-RESINOUS DEPOSITS

The article considered the process of operation of wells, paraffin oil, causing a serious problem during the operation of the well. Physico-chemical methods providing an increase in displacement and coverage coefficients simultaneously for the extraction of film and capillary–retained oil from flooded reservoirs. At the same time, by adding special chemicals to water, it is possible to create solutions that reduce: the interfacial surface tension of water, thereby changing the ratio of the displacing and displaced phase mobility. For this kind of issues, pilot field studies and testing of the optimal technology for cleaning the bottom-hole formation zone (BFZ) from deposits of asphaltene-resinous substances were carried out and 6 production wells were selected for this purpose. Further, the criteria of wells for conducting pilot field tests of the technology for cleaning bottom-hole zones of wells from asphaltene-resinous substances are recommended. A composite composition with a high solvent capacity in relation to asphaltene-resinous substances was selected, the results of laboratory studies to determine the effectiveness of hydrocarbon solvents were given. The volume of the solvent composition was calculated for all selected wells. It is recommended that for processing for each well, a "Plan for processing the bottom-hole zone of the well" was drawn up, and a recommendation was also given that the processing of the BFZ should be carried out without extracting the underground equipment of the well (tubing columns with a pump).

Влияние глубинного положения кровли пласта С2b и межсолевых мульд на добычные возможности скважин левобережной части Астраханского газоконденсатного месторождения

The construction of horizontal wells requires a more accurate prediction of the filtration and reservoir properties of the reservoir for operational correction of their trajectory. The practical significance and relevance of the work consists in substantiating the possibility of the fullest realization of the potential of production wells when drilling new areas on the Left Bank of the Astrakhan gas condensate field. The purpose of the study is to identify the correlation dependencies of watering zones and low porosity and permeability properties on geological factors and to form recommendations for the horizontal wells drilling. The watering of wells is analyzed depending on the position of drilled wells on the structural surface of the productive reservoir C2b, the duration of the period of "waterless" operation of wells, the period of watering and well operation. The features of the location of zones with low porosity and permeability properties of productive deposits are studied. According to the results of the conducted research, definitely: the high value of the water-gas factor and the rapid watering of production wells is due to the high opening marks of the productive horizon (above -3850 m) and zones of vertical fracturing; zones with low porosity and permeability properties of the productive reservoir C2b are confined along the roof of the salt strata P1kir to the deepest areas of salt swally. The following recommendations on the drilling of wells for the fullest realization of their potential have been formed: 1) in areas with a high or low location of the roof of the Bashkir horizon, it is advisable to drill wells with a horizontal profile; 2) when conducting horizontal wells in salt swally and getting into the zones of low porosity and permeability properties during the opening of the productive reservoir, it is necessary to consider the possibility of changing the azimuth in the direction of the side of the swally.

Case Studies and Operation Features of Long Horizontal Wells in Bazhenov Formation

Summary In this study, unique field data analysis and modeling of operating wells with an extended horizontal wellbore (HW) and multistage hydraulic fracturing (MHF) in the Bazhenov formation were conducted. Moreover, a large amount of long horizontal well data obtained from the Bazhenov formation field was used. Wells with extended HW drilling and MHF are necessary for commercial oil production in the Bazhenov formation. Problems can occur in such wells when operating in the flowing mode and using an artificial lift at low flow rates. This study aimed to describe the field experiences of low-rate wells with extended HWs and MHF and the uniqueness of well operations and complexities. It was also focused on modeling various operation modes of such wells using specialized software and accordingly selecting the optimal downhole parameters and analyzing the sensitivity of fluid properties and well parameters to the well flow. The flow rates in wells with extended HW and MHF decrease in the first year by 70–80% when oil is produced from ultralow-permeability formations. Drainage occurs in a nonstationary mode in the entire life of a well, leading to complexities in operation. A comprehensive analysis of field data [downhole and wellhead pressure gauges, electric submersible pump (ESP) operation parameters, and phases’ flow rate measurements] and fluid sample laboratory studies was conducted to identify the difficulties in various operating modes. For an accurate description of the physical processes, various approaches were used for the numerical simulation of multiphase flows in a wellbore, considering the change in the inflow from the reservoir. The complexities that may arise during the operation of wells were demonstrated by analyzing the field data and the numerical simulation results. The formation of a slug flow in low flow rates in a wellbore was caused by a rapid decline in the production rate, a decrease in the water cut, and an increase in the gas/oil ratio (GOR) over time. Based on the results, proppant particles can be carried into the HW and thereby reduce the effective section of the well in case of high drawdowns in the initial period of well operation. Consequently, the pressure drops along the wellbore increased, and the drawdown on the formation decreased. Other difficulties were determined to be associated with the consequences and technologies of hydraulic fracturing (HF). These effects were shown based on the field data and the numerical simulation results of the flow processes in wells. In addition, corrective measures were established to address various complexities, and the applications of these recommendations in the field were conducted.

Recommendations for reducing sanding process in water wells

The history of vertical drainage wells began in 1923 in the United States of America and since 1950 in Uzbekistan. Such scientific researchers as N. Reshetkina, Kh. Yakubov, A Umarov, Z. Pushkarev, N. Nasonov, I. Akhmedov, and other scientists worked on designing and constructing vertical drainage wells. The study aims to develop recommendations for improving the sustainable operation of vertical drainage wells based on their design and construction, considering natural and economic conditions. The relevance of the work lies in the fact that stable operation of wells without sanding will provide: an increase in the duration of good operation without repair, an improvement in water supply in the reclaimed area, drainage of the area suspended on the well, and an increase in economic efficiency. The place of research work is the Syrdarya and Fergana regions of the Republic of Uzbekistan, as well as the Kyzylorda region of the Republic of Kazakhstan. The design of vertical drainage wells differs significantly from water wells (for water supply) in that vertical drainage wells are drilled with a large diameter (800-1260mm) and equipped with gravel filters. They have a shallow depth (35-80m) and large diameters of the filter frame and casing pipe (300-426mm), which significantly affect their costs and determine the territory's drainage area, which is the main task of this type of well. Such wells are operated in the study areas. The article presents data that is the basis for developing recommendations for improving the sustainable operation of a vertical drainage well. Recommendations are given to eliminate the problems of vertical drainage wells.

Predicting the annular pressure behavior during water injection in offshore wells with a transient, multiphysics model

Predicting the pressure behavior of annular fluids during production and injection operations in oil wells became a major research topic in the exploration of deep-water reservoirs. Although pseudo-steady-state models can predict annular pressure buildup in most production scenarios, more robust transient approaches are required in injection operations due to the short time scales involved. This paper presents a new transient thermo-structural model that calculates temperature and pressure profiles during a recycled saltwater injection operation in a well with three concentric annuli. The model was compared with field data acquired uninterruptedly for a seven-day period containing two consecutive well shutdowns. The maximum relative deviation between the numerical results and the field down-hole pressure was lower than 4%. Absolute down-hole temperature deviations were smaller than 5 °C. Furthermore, simulations based on a newly proposed dimensionless inter-annular pressure difference parameter facilitated identifying the risk of thermally-induced casing collapse due to contrasting rates of pressure change between neighboring annuli. The effectiveness of mitigating such risks using rupture disks was evaluated numerically, and the most favorable scenario consisted of rupture disks installed in the two casings connecting the three annuli.

Evaluation and comparison of economic indicators of the method of cyclic operation of wells on the example of the Nydinskaya area of the Medvezhye field

Evaluation and comparison of economic indicators of the method of cyclic operation of wells on the example of the Nydinskaya area of the Medvezhye field

THE DESIGN PROFILE OF THE DIRECTIONAL WELL ON THE NORTHERN GOTURDEPE FIELD

When deciding to use the method of dual completion, the degree of depletion of reserves, the proximity of the oil-bearing contour to wells, the presence of resins and paraffin in the extracted oils, the thickness of productive layers and the non-permeable layers separating them, the state of the production column of wells, etc. are taken into account. The positive effect of applying the technology dual completion is expressed in a reduction in capital investments for the construction of wells for each of the operational facilities, in reducing operating costs and the development period of a multi-layer field, in increasing the production of hydrocarbons and the term of final oil recovery with cost-effective operation of wells. In addition, the use of this technology contributes to an increase in the utilization rate of downhole equipment and the reliability of the downhole installation. When two horizons are operated separately at the same time, the layers are separated from each other by a packer. One or two rows of pumping and compressor pipes descend into the well, which are lowered in parallel or concentrically. With dual completion of two or more horizons, reservoir development can be carried out according to the following schemes: fountain-fountain; fountain-pump; fountain-gas lift; fountain-injection; gas lift-pump; gas lift-gas lift, gas lift-injection; pump-pump; pump-injection; pump-injection. The article considers the experience of drilling a directional exploration well in Turkmenistan in order to trace and clarify the expansion of the area of productive horizons in the coastal zones of the coastal waters of the Caspian Sea. This work can be used for the development of fields in difficult-to-develop shallow waters and to reduce costs during their drilling, as well as to increase the volume of oil produced in order to develop the field using the method of dual completion (accelerated method), without increasing the oil recovery coefficient.

Assessment of the type of reservoir fluid extracted from wells of a gas and oil deposit by the component composition of gas samples

The article considers determination of the type of extracted gas from wells of oil and gas deposits on the basis of the analysis of data on component structure. The rated parameters are used for the comparative assessment of gas compositions prior to development and during the operation of wells. The received results of research will be used by the author for the subsequent quantitative assessment of gas production of different type.

Mechanism of Casing String Curvature Due to Displacement of Surface Strata

One of the main problems of well operation is the risk of uncontrolled leakage of hydrocarbons into the environment. This problem is especially relevant for the long-term operation of wells. The idea for this study was inspired by a real industrial problem that the authors of the article were involved in solving. At several operating gas wells, an abnormal slope of the production tree occurred, which raised the question of the safety of their further operation. An analysis of known studies and current regulatory documents did not allow us to assess the safety of using a gas well based on the measured kinematic parameters of production tree deviations. A mathematical model for the deformation of a package of casing strings when the surface layer of the rock is displaced is developed in the article. A boundary value problem is formulated for differential equations of pipe bending on an elastic foundation. Based on the results of solving this problem, an unambiguous relationship was established between the maximum bending stress in the surface pipe and the angle of inclination of the production tree. The quantitative characteristics of the connection depend on the geometric and mechanical properties of the pipes and on the thickness and mechanical parameters of the formations. It was established that the existing inclination of the production tree can be achieved due to the beginning of the plastic bending of the surface pipe under the slickenside, which does not exclude the exhaustion of the safety margin of the surface pipe and indicates the possible operation of the casing string in a pre-emergency state. In general, the obtained results develop analytical approaches to assessing the behavior of underground structures of a production well in unstable soil bodies.

Conducting emergency operations in wells with narrowed zones in the production string

The article provides information that the production string along the entire length consists of casing pipes of the same type-size with different wall thicknesses, in some cases thicker in the upper part, relatively less thick in the lower part; on the reduction of the inner diameter with some methods of restoring the tightness of casing strings. Conducting emergency operations in such wells stopped during operation by milling the emergency ends or their annulus, as a necessary measure, with milling cutters of a smaller diameter causes even greater deformation of the emergency ends up to breaks. And also for catching the wider lower part of the production string eccentrically located or leaning against the wall of the pipe, due to the impossibility of using a centering device – funnels, down-laid fishing tools without a centering device, although they freely pass through the narrowed zone of the production string located above the emergency end, due to the impossibility of covering with a bell, as well as directing the pipe rod into the inner surface of the fishing pipe, fishing work is unsuccessful. In these cases, the use of an eccentric sub in the assembly of the bottom of the drill string, the use of a milling cutter of the smallest diameter ensures the milling of the emergency end located below the narrowed zone, with a milling cutter of the required diameter corresponding to the inner diameter of the production string, and also provides the possibility of catching an emergency pipe without a centering device. Information about the design features and their advantages in the relevant downhole conditions is given. Keywords: emergency end; milling cutters; fishing tools; BHA; eccentric sub.

STUDY OF THE EFFICIENCY OF HYDROMECHANICAL PACKERS USED IN THE OPERATION OF DELICATED WELLS

The article considers the general shortcomings of packers designed for carrying out geological and technical measures in an open hole. These packer deficiencies can cause problems in the operation of wells, which leads to an increase in non-productive time or even to the loss of a well and, as a result, leads to high costs for oil and gas companies. The design of sliding support elements, centering the structure in the open hole, preventing leakage of the sealing rubber element due to the occurrence of a pressure drop, and subsequently ensuring a reliable packer break, has been studied. Key words: hydromechanical packer, wellbore, sealing element, the packer unit.

PREVENTION OF SAND CLOGGING IN WELLS

A brief analysis of the prevention of sand blockage in wells is considered. One of the most common complications during the operation of wells in Azerbaijani oil fields is sand formation. During sand formation, wells are stopped for a while, their repair takes a long time, and as a result, significant well product losses occur. The sand that comes with the fluid entering the wellbore destroys the equipment and at the same time forms a blockage in the wellbore. The removal of the sand plug requires heavy labor, but sometimes leads to oil losses in many wells and leads to the collapse of rocks in the wellbore zone and the deformation of the production pipeline. The collapse of the bedrock and the prevention of sand congestion are still one of the most pressing issues in the oil industry. Despite numerous scientific studies and mining experiments on the mechanism of sand formation prevention, no universal method has been found to combat sand formation. The collapse of the bedrock and the prevention of sand congestion are still one of the most pressing issues in the oil industry. Keywords: sand plug, well, sand plug removal, well bottom filter, surface filter, well bottom zone

Wyznaczenie najlepszego miejsca montażu urządzeń technologicznych na podwoziu pojazdów naprawczych na polach naftowych

Currently, it is impossible to imagine the repair and drilling of any well without the use of modern mobile equipment. With technological progress, not only new development technologies in the branch of field exploitation appear, but also new equipment with which oil and gas wells are repaired and reconstructed. Today, oil production is mainly carried out by the operation of wells without a pumping derrick, which makes it possible to sharply reduce the cost of metal and funds. Operations of downhole equipment lifting and tripping in a well are carried out using self-propelled mobile units representing tracked or wheeled transport vehicles on which a derrick (mast) with a winch, transmission and hoisting system is mounted. Lifting units are equipped with a mechanism for raising the mast to the working position and lowering it to the transport position. Installations with a lifting capacity of up to 32 tons inclusive are designed for lifting operations during routine underground repair of wells, whereas over 32 tons minimal lift capacity are required during major repairs and well development. The mobile unit is subjected to oscillatory movements both during transportation along unpaved, semi - destroyed, muddy and snow-covered roads to the well (for development, repair), and during well drilling. The frequency of the oscillating movement depends on the state of the uneven road. The unevenness of the road is expressed by spectral functions. In this case, both the chassis and the body of the mobile unit, as well as the technological equipment located on it, are subjected to oscillatory movements. As a result, technological equipment, as well as devices and equipment located on it, lose their accuracy, which leads to accidents both during drilling and during operation. Therefore, in order to minimize the influence of oscillatory movements on the operability of technological equipment, a technique was developed for technological equipment positioning on the chassis of a mobile unit at an optimal scheme according to the proposed method.

Well design development for multilayer horizons for the simultaneous separate operation by one well

The positive effects of applying the technology for simultaneous separate operation (hereinafter referred to as SSO) include the reduction in capital investments for the construction of wells for each of the operational facilities, the cutback of operating costs and the development period of a multi-layer horizon, the increase in hydrocarbon production and the final oil recovery period from profitable operation of wells. In addition, the use of this technology contributes to increasing the utilization rate of downhole equipment and enhancing the reliability of the downhole device. The simultaneous separate operation technology is economically efficient due to the production of additional oil, a high profitability index and a low payback period. Keywords: azimuth, zenith angle; off-vertical; well profile; doublelift tubing; liner filter; packers; valves.

The Oil Industry in Galicia until 1918 in Light of the Records of the Galician Governorate in Lviv

The files kept at the Central State Historical Archive of Ukraine in Lviv are of fundamental importance for research into the issues of the oil industry in Galicia. Of particular note is the largest ensemble in the archive – fond 146: Galician Governorate in Lviv, containing the records of the central government of Galicia. This collection has preserved a rich collection of materials representing various aspects of the development of the oil industry. They dealt with issues of the occurrence of crude oil in Galicia, the acquisition and exploitation of oil plots, the extraction and processing of oil, and the construction and operation of wells and refineries. The information on the state of the oil mines in Galicia, especially in terms of meeting technical conditions, fire protection and occupational safety, is valuable. An important place is held by files depicting issues of the creation of industrial infrastructure, including the construction and maintenance of oil pipelines, the construction of storage facilities, and the railway connection to the plants. The files also contain information on the establishment and activities of domestic and foreign oil companies and joint stock companies in Galicia. Also of interest are materials on the development of the labour movement. Keywords: records of the Galician Governorate in Lviv, kerosene, oil industry, mines, oil companies and joint stock companies.

Управление добычей нефти на основе нейросетевой оптимизации режимов работы скважин на участке опытно-промышленных работ пласта ЮВ1 Ватьеганского месторождения ТПП «Повхнефтегаз»

Optimization of the “mature” fields development in machine learning algorithms is one of the urgent problems nowadays. The task is set to extend the effective operation of wells, optimize production management at the late stage of field development. Based on the task set, the article provides an overview of possible solutions in waterflooding management problems. Production management technology is considered as an alternative to intensification of operation, which is associated with an increase in the produciton rate and involves finding solutions aimed at reducing the water cut of well production. The practical implementation of the “Neural technologies for production improvement” includes the following steps: evaluation, selection, predictive analytics. The result is a digital technological regime of wells that corresponds to the set goal and the solution of the optimization problem in artificial intelligence algorithms using the software and hardware complex “Atlas – Waterflood Management”. “Neural technologies for production improvement” have been successfully tested at the pilot project site of the productive formation of the Vatyeganskoe field. The article provides a thorough and detailed analysis of the work performed, describes the algorithms and calculation results of the proxy model using the example of the pilot area, as well as the integration of the “Atlas – Waterflood Management” and the organization of the workflow with the field professionals of the Territorial Production Enterprise Povkhneftegaz.

ABOUT SKIN EFFECTS OF OBLITERATION AND COMPRESSION

There should be factual information on the skin-effect on each well that reduces oil and gas production for operational work, as well as for the calculation of oil and gas deposits or for the design of field development. Well development and operation experience shows that contamination of the bottomhole zone and deterioration of leakage properties may be associated not only with collution, but also with events such as obliteration and rock compaction. Thus, during the operation of wells, events such as shrinkage and retention of microcatches and capillaries in fractured-porous formations over time are inevitable. The impact of this factor must also be taken into account, as the method of impact on the bottomhole zone and the compression of formations under the influence of overburden pressure. Such events should be attributed to the factors that increase the resistance of the bottomhole zone and should be studied as an object of research. The discovery of deep hydrocarbon deposits and their development experience show that failure to take into account the deformation of the porous medium as a result of a drop in formation pressure during development reduces the reliability of development parameters. The commissioning of deeper oil, gas and gas condensate fields requires the interpretation of mining data and the development of methods for hydrodynamic research of wells, taking into account the density of layers. Compression of stratified formations with significant deformation during development and the impact of this effect on the development process significantly improves the theory of filtration, taking into account the compression of formations in gas-hydrodynamic modeling, interpretation of mining data and other issues. In order to study and assess the skin effect associated with obliteration and compression, it is necessary to analyze real well data during the operation of productive oil layers. Three of them used the concepts of "normal" production, productivity, as well as the lowest production and productivity of the oil well in operation, and analyzed the performance of the well for several years. This analysis is based on the fact that production changes from depression to exponential law. The article puts forward a version of the existence of obliteration and compression skin effects along with colmatation in a practical example, and a methodology has been developed and tested to determine them. It has been found that during real depressions for collectors, these skin effects (So-c) may be greater than the colmatation skin effect (Scol). However, in practice, the value of the Scol is not accurately determined by one measurement based on the pressure build-up curve. The skin effect of obliteration and compression (So-c) is simply often negligible. In order to assess the skin-effect of colmotion and obliteration-compression in the reduction of well production, calculations were made at the values of the contour radius Rk = 150 m and well radius rq = 0.1 m. As a result, it was determined that the production of wells can be reduced by 64% due to the obliteration-compression effect. This is about 10 times more than skin effect of colmotation. It was determined that the skin-effect of obliteration and compression had a greater effect on productivity should be taken into consideration when forecasting well production. Keywords: obliteration, skin effect, collector, productivity, production, pressure