Karachaganak Field Research Articles

A lookback study of well performance using borehole image data

The main objective of this work is to understand the impact of fracture, stress, drilling direction, and other reservoir properties on the production performance of a horizontal well (HW) in the Karachaganak Field. Taking advantage of the 70 available borehole image logs helped extend the analysis beyond individual wells to a field scale evaluation. Three analysis methods were developed to progress with the study: a favored drilling direction map, a Reservoir Property Filter, and crossplotting for multiple reservoir properties to gauge well performance. Results showed linear, nonlinear, and multidimensional relationships. The findings will be used to guide future HW drilling optimization, support dynamic modeling, and improve the model’s predictability for effective reservoir management.

Study of the efficiency of well repair at the Karachaganak field

The assessment of the effectiveness of the choice of formulations of clay-free inhibited salt solutions, recommended for washing when drilling side shafts and horizontal sections, based on the study of biopolymers, in the conditions of the Karachaganak deposit, is considered. The duration of the fountaining of production wells at the Karachaganak field depends both on the methods used to increase the oil yield of layers (primary and secondary) and on the dimensional characteristics of the fountain system for lifting well production. As a result of a gradual decrease in reservoir pressure and water inflow into the downhole zone of the well, its stability is significantly reduced, the filtration characteristics of the reservoir deteriorate, the formation of mineral deposits, sand and gas hydrate plugs increases, and the corrosion activity of production increases. And as a result, the production capacity of producing oil and gas condensate wells is significantly reduced. The character of the composition of the reservoirs of the deposits of the Karachaganak deposit, in the overwhelming majority, contain clayey cement. At the same time, the "swelling" of clay rocks is a significant reason for the decrease in productivity of production wells. Collectors with low permeability with practically irreversible "internal clogging" are especially sensitive to this effect. The use of technological fluids has been found to be the most effective – solutions containing a biopolymer as the main component, possessing pseudo-plasticity and contributing to high-quality cleaning of the bottom hole from mud, as well as the maximum removal of mud residues from the well system, which have a minimal polluting effect on reservoir reservoir systems, since biopolymer the substance entering the collector is enzymatically decomposed after a certain time. The use of the composition of the inhibitory biopolymer salt solution based on the KCl complex salt (potassium chloride-electrolyte) will allow to fully preserve the properties of the productive layer. For maximum isolation of the watered downhole zone of the formation, the authors propose to use a tamping solution on an adhesive basis with properties sufficient for reliable isolation. Injection of tamping solution under pressure into the layer will increase the strength of the cement stone by an average of 1.5 times.

METHODOLOGY FOR DETERMINING THE MAXIMUM ANHYDROUS FLOW RATE OF A HORIZONTAL OIL WELL IN DEPOSITS WITH PLANTAR WATER

The article is devoted to the use of approximate methods for determining the productivity of horizontal oil wells and comparing the results of flow rate calculations by these methods on the example of an oil facility of the Karachaganak field. Watering or gassing of the oil-bearing interval significantly reduces the phase permeability of oil and leads to a very significant decrease in oil flow rate. Therefore, technologies that minimize the process of cone formation are of great practical importance. From the point of view of the influence of flooding on the technological mode of operation of a horizontal oil well and the possibility of determining the anhydrous flow rate, it follows that the following possible options are proposed to avoid flooding of the well:- the use of horizontal wells with the appropriate location of the horizontal trunk, depending on the proximity to the oil-water contact (VNK), taking into account the magnitude of the depression created on the formation; - selection of the appropriate design of the well, the length and diameter of the fountain pipes in the horizontal part of the trunk, providing the amount of depression necessary to slow down the pace of movement of plantar water.

Factors influencing the productivity of horizontal wells on an example of the karachaganak deposit

This article examines the factors affecting the productivity of horizontal oil wells in the example of the oil reservoir of the Karachaganak field. The paper presents several methods for calculating the productivity of horizontal wells, taking into account the geometry of the drainage zone. The formulas describing the productivity for each of the methods are analyzed, and the results of calculating the flow rates of horizontal wells for various parameters are presented. The authors considered the following methods: Yu. P. Borisov, S. D. Joshi F. M. Method Giger, method G. I. Renard, J. M. Dupug and Z. S. Alieva, V. V. Sheremet. All methods are based on the assumption of a stationary filtration regime, uniformity of the reservoir, and the location of the horizontal wellbore symmetrically or asymmetrically in thickness. Calculations were performed for well No. 918 in the Karachaganak field using various values of reservoir thickness, horizontal wellbore length, permeability, drawdown, and distance to the feed loop.

"ANALYSIS OF WELL COMPLETION COMPLICATIONS AND THEIR ELIMINATION IN THE KARACHAGANAK FIELD"

"By examining well completion issues, the paper will demonstrate the importance and beneficial effects of using multi-stage selective acid treatment technology to regulate reservoir development. The original goals for the Karachaganak field were a review of the field’s operating conditions, the building of the first plant for producing gas and gas condensate, and the design of the production circuit. After the separation of products contract was signed, new goals were added, such as accelerating oil well commissioning, increasing gas condensate production over the long term, and pumping at least 40 % of the gas back into the layer. Numerous well completion techniques have been improved thanks to technical developments, including applying tubing while sealing metal-to-metal threaded connections, omitting the use of a circulation valve above the packer, and utilizing a downhole shut-off valve. The field development project’s Phase 2M got under way in 2003. An innovative well completion technique was used in the Karachaganak field, which used acid fracturing in an open hole with packers and circulation valves to separate the intervals. In 8 horizontal wells, the multistage stimulation approach has proved effective, saving both time and money. In one of the wells, selective stimulation was made achievable by an acid treatment plan that met zonal injectivity standards. Increased well productivity, flow distribution, gas, water, and drawdown control have all been benefited by multistage selective acid stimulation. "

Lithological and stratigraphic characteristics of the upper permian and triassic deposits of the Karachaganak oil and gas condensate field

The article considers the results of part of the research, groundworkss, as well as the experience gained in the implementation of the project to study the core of the Triassic and Tatar horizons of the Karachaganak field. This project included both direct work with core material, conducting a series of laboratory studies on it in order to determine the conditions of sedimentation, understanding their extent, determining the age of rocks, their qualitative and quantitative characteristics, and facies modeling to obtain facies maps, correlation schemes and profiles. One of the most interesting and important stages of the project implementation was biostratigraphic analysis and the construction of a correlation scheme on its basis in order to conduct a qualitative correlation of the section, which is the basis for identifying the conditions of sedimentation and understanding their strike in space.

Peroxide Oxidative Desulfurization of the Gas Condensate from Karachaganak Field

Peroxide Oxidative Desulfurization of the Gas Condensate from Karachaganak Field

Oxidative desulfurization of the straight-run gasoline fraction from the gas condensate of the Karachaganak field

An annual increase in the consumption of the automobile fuels makes us look for new ways of their obtaining. It is also important that the environmental and operational requirements for the quality of the motor fuels, obtained during oil production (associated petroleum gas, gas condensate) are systematically made more rigorous. One of the ways to solve the problems described above is to use the process of oxidative desulfurization to improve the quality of the petroleum products. In this case, oxidative desulfurization of the straight-run gasoline fraction, obtained from the gas condensate of the Karachaganak field, has been carried out. The oxidation process has been carried out with hydrogen peroxide in the presence of salts of the transition metals, molybdenum and vanadium. The optimal technological parameters (Patm, T=600C, 2 h, H2O2:S=4:1 (mol), Me:S=1:100 (mol)) of the oxidation process for the straight-run gasoline fractions have been selected. Under the optimal conditions of the oxidation process, the total sulfur content has been reduced by 89.9%. It has been shown that the molybdenum compounds exhibit greater activity in the oxidation of sulfur-containing compounds at a temperature of 600C, as compared to the vanadium compounds. A schematic diagram of the purification of the gasoline fractions from the sulfur-containing compounds by oxidative desulfurization, followed by its extraction desulfurization with the most effective N,N-dimethylformamide has been presented.

Microstructural wettability of oil and gas condensate zones of the Karachaganak field

The Karachaganak field is represented by gas condensate and oil zones, a convenient object for studying changes in microstructural wettability during the transition from one zone to another. Microstructural wettability was characterized by a hydrophobization coefficient, Ѳн, which determines the proportion of the pore surface area occupied by adsorbed hydrocarbons. It was found that Ѳн of the samples of the gas and gas condensate zones is the same (on average 0.140), the oil zone - on average 0.250. Analysis of the IR spectra of extracted hydrocarbons showed that the microstructural wettability of the oil zone contains more aromatic, aliphatic, oxidized and sulfur-containing structures and fewer branched structures than in the gas condensate zone. The microstructural wettability of carbonate reservoirs depends on the hydrocarbon composition of the adsorbed oil. Keywords: microstructural wettability; hydrophobic coefficient; hydrocarbons; spectral coefficients.

Constraining stratal architecture and pressure barriers in the subsalt Karachaganak Carboniferous carbonate platforms using forward stratigraphic modelling

Predicting reservoir quality and pressure barriers is a challenging task in carbonate systems. In this paper, we present new model results from the Lower Carboniferous Serpukhovian carbonates in the Karachaganak Field (Northern Kazakhstan), which is characterized by complex facies architectures and reservoir compartmentalization. The Serpukhovian sequence at Karachaganak is poorly imaged by seismic due to the presence of thick Permian salt canopies. The carbonate sequence comprises two carbonate build-ups: a larger Main build-up (MBU) in the eastern portion of the field, and a smaller isolated Western build-up (WBU). We used diffusion-based DionisosFlow forward stratigraphic modeling (FSM) coupled with a CougarFlow sensitivity analysis workflow to (1) review sub-salt seismic horizon picks based on process-modeling constraints, (2) understand the regional controls on the stratigraphic stacking patterns, (3) understand the distribution of reservoir facies, including potential lateral pressure barriers, and (4) constrain the impact and uncertainties of our choice of boundary conditions in the model. Results point out the need for revisions of existing reservoir-scale static models as FSM simulations indicate that the current seismic reflector pick for the base of the Serpukhovian Stage below the WBU is incompatible with the seismic geometries and facies distribution for this system. To reconcile modelling results with existing seismic geometries, the base of the Serpukhovian stage is expected to be about 180 m higher in the stratigraphy. This suggested revision is also supported by the drilling of a recent well that penetrated the top of the Permian 200 m higher in the stratigraphy on the WBU than anticipated. Modeling results also show that fast regional subsidence rates were the primary control for the Early Serpukhovian aggradational stacking pattern, but that slowing subsidence rate during the Late Serpukhovian due to the Uralian orogeny resulted in a switch to progradational sequence patterns. The forward stratigraphic model additionally demonstrates the major role of wind direction and short-term eustatic changes on the presence and distribution of reefs and breccia reservoir facies. Models show that the clinoforms’ angle of repose varies between the leeward and windward sides of the build-up, which leads to the deposition of mud draping on the leeward side that acted as fluid barriers. The presence and distribution of the reservoir and mud facies in the model can explain the observed reservoir compartmentalization at Karachaganak. Finally, our forward stratigraphic modeling workflow coupled with uncertainty analysis provides new quantitative constraints to understand the impact of diffusion coefficients and sediment production rates on the vertical and lateral reservoir heterogeneities and associated lateral pressure-barriers.

Trends of change in demographic indices of population in the area of oil and gas deposits of the republic of Kazakhstan

According to assured resources of hydrocarbons the Republic of Kazakhstan (RK) is among ten largest oil countries in the world, trailing only some states of the Middle East, Latin America, as well Russia and the USA. Public health state is the one of most important indices of social development, the manifestation of the economic and sanitaryhygienic welfare, as well as national defense capability and cultural potential of the state. In relation with the intensive development of oil and gas fields the problems of environmental protection and healthcare of the population in these regions occur critically. Therefore, it causes keen interest both from the side of researches and practical health care workers. Rapid development of the oil and gas industry leads to changes in a medical and demographic situation of given regions that is related both with the natural migration of the population and other migratory processes. According to data of the Ministry of Energetics and natural resources of RK, the Karachaganak oil-gas condensate deposit is considered to be the one of the largest in the world. For the next 40 years, the field is becoming the stable financial donor of the country. Currently Karachaganak field is considered to be the one of the largest investment projects in Kazakhstan. The studied oil and gas condensate field is located in the Burlin district of West Kazakhstan region, which is 140 km far from the city of Uralsk and 160 km far from the city of Orenburg. The field was discovered in 1984.

Modeling of Karachaganak field development

Management of a geological deposit includes the study and analysis of oil recovery, identification of factors influencing production performance and oil-bearing rock flooding, reserve recovery and other indicators characterizing field development in general. Regulation of oil deposits exploitation is a mere control over the fluid flow within a reservoir, which is ensured through the designed system of development via continuous improvement of production and injection wells placement, optimum performance modes, service conditions of downhole and surface oil-field equipment taking into account various changes and physical-geological properties of a field when using modern equipment to obtain the best performance indicators.

HIGHLY ACTIVE CATALYSTS FOR OXIDATION OF THIOLS

The problem of disposal of toxic and corrosion-active sulfhydryl substances (deodorization), natural hydrocarbons is relevant to operational and environmental aspects. One method of removing these impurities is catalytic oxidation to non-toxic disulfide form. The message shows the results of a comparative study of the oxidation reaction of thiols by oxygen to disulfides in hydrocarbon media, catalyzed by complexes of copper salts (I, II) with various nitrogen-containing bases. As nitrogen-containing ligands, mono - and diethanolamine with different C4-C18 hydrocarbon radicals were used. It is established that water-soluble catalyst composition on the basis of monoethanolamine and the hydrocarbon-soluble complex of copper Cu(II) with N-octadecyldiethanolamine exhibits low activity in the oxidation of 1-octanethiol. It was found the activating effect of HCl on the activity of catalysts in various hydrocarbons (model mixture, vacuum gasoil, naphtha and gas condensate of the Karachaganak field), which allows for an exhaustive oxidation of thiols with the initial concentrations ≥1000 ppm. However, the introduction of hydrogen chloride is accompanied by the appearance of corrosion. The introduction of corrosion inhibitors have led to the complete deactivation of the catalysts. The high-performance catalytic system based on CuCl2/CuO was designed, for which we found the optimum ratio of catalyst/inhibitor, to eliminate the corrosion effect while maintaining a high level of activity. The kinetics of the oxidation reaction of the sulfhydryl derivatives by oxygen was studied. It was found that regardless of the nature of the hydrocarbon media, for all investigated catalysts a zero order on concentration of the thiol and close to first order on the catalyst concentration is observed. The use of developed catalysts and purification technology in the industry will reduce the environmental hazard during the transportation and storage of petroleum products.Forcitation:Pletneva I.V., Gavrilov Yu.A. Highly active catalysts for oxidation of thiols. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 70-73.

Continuous deep microseismic monitoring of the Karachaganak Field, Kazakhstan: integrating reservoir geoscience, drilling and engineering

The Karachaganak Field is an oil and gas condensate supergiant field located in the western Kazakhstan Pricaspian Basin. As part of the challenge to improve reservoir knowledge, KPO has been continuously monitoring the reservoir using a microseismic array deployed downhole since February 2009. Continuous deep recording of microseismic activity is an innovative technique for reservoir monitoring; progressive refinements were made to fine-tune the acquisition and processing techniques. By December 2010, 8074 events had been detected and, from this group, 2556 events have been located. Events within the reservoir were recorded up to 8 km from the array to a depth of 5 km with moment magnitudes (Mw) ranging from −2.4 to +1. Microseismic events are continuously located and their spatial and temporal distribution analysed. This basic analysis is the input to an integrated study that considers the static model for the reservoir, in addition to dynamic and operational aspects such as production and injection rates, pressure baffles, drilling behaviour and casing perforations. The results to date indicate valuable reservoir information concerning the location of lateral and vertical reservoir pressure baffles and delineation of zones of instability at the reservoir–seal interface, important for well integrity issues. This new information is helping to improve dynamic and geomechanical reservoir models and also wellbore stability predictions. This article presents the details of the Karachaganak microseismic array and how microseismic events were located. Discussion follows on the interpretation and the possible impact on reservoir monitoring and drilling. The Karachaganak array is one of the deepest installations of a passive microseismic monitoring system and also represents one of the longer periods of continuous monitoring, with two years of data available.

Controls on improved sub-salt reservoir imaging at the giant Karachaganak Field, Kazakhstan

In western Kazakhstan there are several world class hydrocarbon fields, including the onshore Karachaganak Field. The geological setting is very challenging for the seismic imaging techniques where deep carbonate platform targets underlie a complex overburden including diapiric and detached salt structures. Furthermore, the extensive oil field infrastructure generates a noisy environment for seismic acquisition and reduced access for vibroseis trucks. KPO conducted an extensive integrated feasibility study for a new survey, complemented by a seismic acquisition test in 2008 which confirmed the need for dense source and receiver coverage, long offsets and wide azimuths to optimize imaging of the pre-salt targets. The survey was acquired in 2009 and survey execution exceeded local and international standards. It was the highest channel survey acquired in Kazakhstan and when fully depth image processed it will yield a high spatially sampled seismic volume, with improved resolution and structural definition. The application of the latest technology and techniques will enable better characterization of this complex carbonate reservoir, adding future value by better placement of wells and reducing overall costs for the ongoing development of the field.

Application of Horizontal Wells To Reduce Condensate Blockage in Gas/Condensate Reservoirs

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 130996, ’Application of Horizontal Wells To Reduce Condensate Blockage in Gas/ Condensate Reservoirs,’ by Nathan Miller, SPE, Hadi Nasrabadi, SPE, Texas A&M University-Qatar, and Ding Zhu, SPE, Texas A&M University, prepared for the 2010 SPE International Oil & Gas Conference and Exhibition in China, Beijing, 8-10 June. The paper has not been peer reviewed. Much of the world’s gas reserves can be found in gas/condensate reservoirs. These reservoirs, from a recovery and deliverability standpoint, can have significant differences from oil reservoirs. When the pressure, either in the wellbore or in the reservoir, drops below the dewpoint pressure, a condensate phase appears that reduces gas production significantly. In this study, horizontal wells were used in a giant gas/condensate reservoir (North field, Qatar) to reduce the condensate blockage. Critical questions are: What fraction of a horizontal well’s increased gas production results from the increased formation contact and what fraction results from reducing condensate blockage? Introduction The largest gas/condensate reservoirs include the Arun field in Indonesia; the Cupiagua field in Colombia; the Karachaganak field in Kazakhstan; the North field in Qatar, which borders with the South Pars field in Iran; and the Shtokmanovskoye field in the Russian Barents Sea. All of these fields have one thing in common—condensate blockage. Condensate blockage occurs when a liquid phase forms around the wellbore because the pressure falls below the dewpoint pressure. Production performance can decrease significantly if these condensate-banking effects are not understood at the beginning of field development. Retrograde gases exhibit a lower gas/oil ratio (GOR) limit of 3,300 scf/STB and an upper GOR limit of 150,000 scf/STB. Retrograde gases have stock-tank liquid gravities between 40 and 60°API and can be lightly colored orange, brown, or greenish or can be clear. The North field is a massive offshore gas/condensate reservoir with more than 900 Tcf of proven natural-gas reserves. The abnormally pressured field covers more than 6000 km2. As Fig. 1 shows, the North field adjoins Iran’s South Pars field, which has 280 Tcf of recoverable natural-gas reserves. The initial reservoir pressure was 5,300 psi, and the initial reservoir temperature was 220°F. The field produces from a carbonate reservoir called the Khuff formation (late Permian to early Triassic). The Khuff formation consists of four noncommunicating, highly stratified layers. Discovered in 1971, North field appraisal drilling occurred over the next 14 years to quantify the reservoir-gas accumulations and to determine the reservoir-fluid and geological characteristics. The Alpha Project began in 1991 to develop the field’s reserves by producing natural gas and condensate from the Lower Khuff. The first concession was awarded in 1993, the first delivery of condensate occurred in 1996, and the first delivery of liquefied natural gas took place in 1997.

An Integrated Approach To Obtain Reliable Permeability Profiles From Logs in a Carbonate Reservoir

Summary Permeability is one of the key petrophysical parameters in reservoir evaluation. Information about permeability is commonly derived from cores and test data, which generally cover only part of the reservoir section, but can also be derived from logs and then extrapolated to uncored intervals and wells. Two logs provide such information: acoustic and nuclear magnetic resonance (NMR). In the Karachaganak field, an approach based on the acoustic tool was preferred because of the textural characteristics of the vuggy carbonate reservoir. The approach relies also on the use of image logs to obtain a detailed description of the reservoir-rocks texture and to discriminate between rocks with primary interparticle porosity or very small vugs and lithotypes with multimodal distribution of pores, enlarged vugs, and touching vugs. More than 900 m of core have been used to validate the permeability log derived from the analysis of Stoneley waves in 25 wells from this field. A correlation between the validated log-derived permeability and the textural facies from image logs has allowed the relationship between permeability variations and the geological framework to be established. The results have been compared with dynamic data from production logging through the definition of flow units from Stoneleywave-derived permeability and porosity-log data and the use of a stratigraphic-modified Lorenz plot (SMLP) to identify possible fluid-entry points. Three main permeability trends have been identified: For undolomitized or patchily dolomitized biohermal deposits for pervasively dolomitized lithologies characterized by lower mean permeability values for facies characterized by well-developed vuggy porosity with enhanced dissolution phenomena (i.e., touching vugs and microfracturing) Also, well-test results have highlighted the occurrence, in some wells, of very high k values in the biohermal deposits, which are clearly unmatchable by log-derived matrix permeability. Open fractures have been observed in these wells on the image logs, thus suggesting that the enhanced permeability and the improved well performances have to be related to their presence. The comparison of log-derived permeability and well-test results has given a new perspective in the interpretation of well-test results with respect to the geological framework and a well-defined sequence-stratigraphic model. The extension of this methodology to new wells could improve knowledge of the petrophysical characteristics of the reservoir and allow better prediction of reservoir productivity.

3D ray-trace modeling to assess the effects of overburden and acquisition geometry on illumination of pre-evaporite reservoirs in Karachaganak Field, Kazakhstan

The specific goal of this study was to gain a clearer understanding of the effects of stratigraphically complicated overburden and acquisition geometry on amplitudes at and close to the Tops of pre-evaporite reservoir reflectors in Karachaganak Field in Kazakhstan (Figure 1). The 3D ray-trace modeling revealed significant irregularities in illumination coverage and considerable amplitude variations at the pre-evaporite reservoir levels. The results demonstrated that these illumination irregularities can be attributed to four discrete causes: thick salt bodies varying in lateral geometry and exhibiting complex boundaries; rapid lateral velocity changes within carbonate and evaporate bodies; steep dip; and rugged topography of reservoir interfaces. The combined effects of these factors resulted in severe raypath bending and distortions. These distortions not only lead to irregularities in the fold-of-coverage and reduced presalt reflection amplitudes but also tend to create traveltime anomalies and artifact...

ABSTRACT: Extensive Dolomitization and Anhydrite Cementation of a Permo-Carboniferous Isolated Carbonate Platform by Large-Scale Seawater Circulation: Karachaganak Field, North Caspian Basin, Kazakhstan

ABSTRACT: Extensive Dolomitization and Anhydrite Cementation of a Permo-Carboniferous Isolated Carbonate Platform by Large-Scale Seawater Circulation: Karachaganak Field, North Caspian Basin, Kazakhstan

ABSTRACT: Evolution of the Geologic Model of the Karachaganak Field, Northwest Kazakhstan

ABSTRACT: Evolution of the Geologic Model of the Karachaganak Field, Northwest Kazakhstan