Condition Of Wells Research Articles

Inverse Problem of Permeability Field under Multi-Well Conditions Using TgCNN-Based Surrogate Model

Under the condition of multiple wells, the inverse problem of two-phase flow typically requires hundreds of forward runs of the simulator to achieve meaningful coverage, leading to a substantial computational workload in reservoir numerical simulations. To tackle this challenge, we propose an innovative approach leveraging a surrogate model named TgCNN (Theory-guided Convolutional Neural Network). This method integrates deep learning with computational fluid dynamics simulations to predict the behavior of two-phase flow. The model is not solely data-driven but also incorporates scientific theory. It comprises a coupled permeability module, a pressure module, and a water saturation module. The accuracy of the surrogate model was comprehensively tested from multiple perspectives in this study. Subsequently, efforts were made to address the permeability-field inverse problem under multi-well conditions by combining the surrogate model with the Ensemble Random Maximum Likelihood (EnRML) algorithm. The research findings indicate that modifying the network structure allows for improved integration of the outputs, resulting in prediction accuracy and computational efficiency. The TgCNN surrogate model demonstrated outstanding predictive performance and computational efficiency in two-phase flow. By combining the surrogate model with the EnRML algorithm, the inversion results closely aligned with those from the commercial simulation software, significantly improving the computational efficiency.

WELL STRING LEAK DETECTION USING MACHINE LEARNING MODELS

Currently, the issue of correct and timely assessment of the technical condition of wells is quite acute due to the development of fields at a late stage, high water cut of the well product, as well as the aging well stock. Traditionally, geophysical surveys are used to determine the technical condition of the production string, which make it possible to determine the presence of a disturbance, as well as its interval. However, due to the heavy workload of field technicians, it is not always possible to send a geophysical batch in a timely manner to check the technical condition of the well string. This fact entails oil shortages, an increase in the percentage of water cut, a negative impact on the environment, an increase in unproductive injection, as well as a decrease in target economic indicators. It is also worth noting the high risk of "idle" travel, when it is not possible to detect the presence of violations in the production casing.As a solution to these problems, the authors proposed a new technique for assessing the technical condition of the column based on a machine learning model. Chemical analysis of the water, the age of the well, the number of repairs carried out on the well, the dynamics of well operation, as well as its structure are the main features for which well leakage is predicted. The obtained signs are processed, loaded into a machine learning model, and then a specialist is given a real-time conclusion about the presence of a well leak. As a result of the experiments, it was determined that the CatBoost model on the sample, taking into account the class balance, showed the best quality according to the F1-measure metric. The authors interpreted the obtained results of model prediction based on the effect of individual features on the probability of leakage of the production casing of the well both in the whole well stock and for each case separately. The following features have the greatest impact on the condition of the string: well age, sulfate content, specific gravity of water, as well as primary salts.This approach can significantly reduce decision-making time, increase the efficiency of detecting leaks in wells, and increase economic targets.The result of this work is a methodology for detecting leakage of the production casing, as well as an indirect method for diagnosing and predicting the degree of fatigue of the production casing and a certain share of the risk of leakage.

Diagnostics of the technical condition of wells drilled through freshwater horizons using active thermometry

Relevance. Recently, ESG (Environment, Social, Governance) principles have been given an important role in the agenda of oil and gas companies – this is an actively developing global trend in the modern business environment. One of its key aspects is a responsible attitude to the environment, increasing the priority of solving environmental problems arising from the extraction of hydrocarbons. A significant environmental problem is, in particular, pollution of freshwater horizons during oil production due to their poor-quality insulation during well cementing. At the same time, in the space of the well behind the casing, there is a flow of borehole fluid to freshwater horizons, which has a negative impact on the environmental situation in this region. In this regard, monitoring the technical condition of wells crossing freshwater horizons is an important and urgent task. Object. An operational well drilled through freshwater horizon, in which geophysical studies are carried out by the method of active thermometry – local heating of the casing section is carried out and the dynamics of the temperature field in it is studied. Aim. To identify qualitative patterns and obtain quantitative estimates of the effect of the fluid flow in the space behind the casing (column space) on the temperature field in the casing. Methods. Numerical mathematical modeling of thermal and hydrodynamic processes in a well using the software package Ansys Fluent (ANSYS Academic Research CFD license, agreement with Bashkir State University dated 06/15/2020). Results. The authors have studied the influence of a plane-parallel horizontal fluid flow of the freshwater horizon on the azimuthal temperature distribution of the casing string during induction heating. It is shown that in the case of leakiness of the cement ring in the interval of the freshwater horizon, an inhomogeneity of the azimuthal temperature distribution of the column is observed, reaching a value of few more K. The authors carried out the simulation of induction heating in the well with liquid column flow to the interval of the freshwater horizon. It is shown that the sign indicating the overflow is the occurrence of a temperature disturbance area vertically above the induction heating interval with a length of more than 1 m. In general, the results of the performed studies show the informativeness of the active thermometry method in relation to the diagnosis of the technical condition of wells drilled through freshwater horizons.

Complex of hydrodynamic studies of wells and formations at the Uzen field

The effectiveness of monitoring the development process depends on the availability of complete and high-quality information about the hydrodynamic parameters of productive formations, reservoir reservoir properties, technical condition of wells, etc. The purpose of oil, petroleum gas and reservoir water research is to obtain comprehensive data on their properties and composition, which are within the productive horizons of deposits, as a rule, are fickle. Ignoring the heterogeneity of oil properties over the area of the deposit and the lack of control over changes in physico-chemical properties during the operation of the field can lead to serious errors in predicting the parameters of field development. One of the most important sources of information is hydrodynamic (field) studies of formations and wells. The advantage of hydrodynamic methods for increasing oil recovery is that they are relatively easy to implement and do not require large economic costs. At the Uzen field, the assessment of the initial productive and filtration characteristics of the formations was carried out on the basis of studies of steady-state filtration (MSS) performed during testing of oil-saturated reservoir intervals during exploration and at the initial stage of industrial development of the field when the deposit was operating under natural depletion mode. The article presents the results of a study by the method of steady-state selections (MSS), a study by the method of pressure recovery (PRC).

Application of borehole cameras in the field of Engineering Geology and Hydrogeology

The use of borehole cameras in Bulgaria is increasingly used in hydrogeology and engineering geology. The resulting photographs and movies contribute to solving problems related to the study and assessment of the condition of water supply wells, as well as to obtain a clear picture on the assessment of rock massifs for their suitability for various types of construction. Borehole cameras on the territory of our country are more widely used in the field of hydrogeology compared to engineering geology. The purpose of this article is to present the possible applications of this technology, which has been improved over the years, for the study of rock massifs in their study for various infrastructure objects. Also. to shed light on the benefits of using boreholes in surveying the various water sources.

Применение нанороботов в нефтегазовой отрасли

In order to increase oil recovery in oil fields the possibilities of using reservoir nanorobots in the oil and gas industry have been investigated. Nanorobots are micro- and nanomechanical systems capable of being injected into an oil reservoir to study and modify its properties. The main attention is paid to solving the problem of oil availability in the reservoir which is achieved by creating mechanical channels and changing the physico-chemical characteristics 
 of oil words, taking into account key factors - the reliability and durability of nanorobots, their ability to work in extreme field conditions. The importance of developing a specialized infrastructure for effective management and control of nanorobots, including software, as well as a communication system for data exchange between nanorobots, is emphasized. The ability of nanorobots to interact with each other and solve problems related to the optimization of oil production processes is considered. It is noted that nano-robots can be used to study and monitor the condition of wells, enhance production processes, improve the properties of materials, as well as in repair work. Before using this technology widely in the oil and gas industry, it is necessary to carry out a detailed study in order to determine the optimal methods of implementation and to solve issues of safety and reliability of such a system.

Carbon isotope evidence for shale gas preservation conditions and large methane release over million years: A case study of shale gas reservoirs of Wufeng and Longmaxi Formations in the Sichuan Basin

Although carbon isotope reversal and its reasons in shale gas reservoirs have been widely recognized, the application of the reversal is yet to be investigated. A study on high-maturity shale from Wufeng and Longmaxi Formations in the Sichuan Basin not only reveals the relationship between the degree of isotopes inversion and the production capacity (e.g., estimated ultimate recovery (EUR)) of the gas well but also indicates the preservation conditions of shale gas reservoirs. (1) Although there are differences in gas isotopes in different shale gas reservoirs, the isotope fractionation of shale gas is small during the production stage of gas wells, even when the wellbore pressure drops to zero. The main cause of the difference in carbon isotopes and their inversion degree can be the uplift time during the Yanshan period and the formation pressure relief degree of shale gas reservoirs in distinct structural positions. Thus, carbon isotope inversion is a good indicator of shale gas preservation condition and EUR of shale gas wells. (2) The degree of carbon isotope inversion correlates strongly with shale gas content and EUR. The calculation formula of shale-gas recoverable reserves was established using Δδ13C (δC1-δC2) and EUR. (3) The gas loss rate and total loss amount can be estimated using the dynamic reserves and isotopic difference values of gas wells in various shale gas fields, which also reflects the current methane loss, thereby demonstrating great potential for evaluating global methane loss in shales.

Sand architecture interpretation and modeling with few wells in the offshore — Case study of X36 area in the Xihu Depression, East China Sea, China

The sand architecture interpretation and modeling of the different orders of sedimentary bodies are of great significance for the efficient development of the unconventional reservoir. However, sand architecture interpretation and modeling using a small amount of observation information are extraordinarily difficult. We took the X36 gas field in Xihu Sag as an example to study the distribution and superimposition characteristics of sandbodies under the influence of tides. We proposed a set of architecture characterization and modeling methods suitable for the condition of a few wells. First, we extracted a variety of seismic attributes from the original seismic data, and we fit the correlations between seismic attributes and sandstone thickness interpreted by logging. Then, we classified and integrated the seismic attributes with a high correlation to calculate the fusion seismic attributes. The fusion seismic attribute has a higher correlation with sandstone thickness. The boundary of the sandstone in the fusion seismic attribute is clearer than a single attribute. We established the sand body distribution model of the study area with the constraints of the fusion seismic attribute and the distance attribute volume. The results indicated that the sand body distribution in the model was more consistent with the sand body development model under the influence of the tide. The results can guide architecture characterization and remaining oil potential tapping of the oil and gas fields offshore.

A Study on the Integrity Evaluation of Cement Sheaths for Deep Wells in Deep Water

The complex temperature and pressure conditions of deepwater wells have a serious impact on cementing quality. Therefore, the integrity of the cement seal becomes a critical factor that can restrict the safety of the wellbore, especially for wells ranging from the conventional deep water to deep water with more prominent deep stratum problems. The operating conditions of deep wells in deep water (referred as the dual-deep well) are complex and harsh. For the conventional evaluation device, it is difficult to accurately simulate the alternating HTHP conditions and to clarify the location and situation of the cement sheath leakage, which directly leads to the deviation of the evaluation results from the engineering reality. To solve this defect, based on the condition and structure characteristics of dual-deep wells, a device and method for casing/cement sheath/formation seal integrity evaluation for dual-deep wells at HTHP has been developed and established. Combined with the analysis of microstructure and micromorphology, the sealing ability and integrity of different cement slurry systems were evaluated. Through this study, a set of cement slurry systems suitable for dual-deep wells is selected that can satisfy the requirements of dual-deep wells with excellent isolation ability and seal integrity under temperature and stress changes. The research results provide a reference for deepwater wells’ wellbore integrity evaluation and research.

INV-FLOW: New Possibilities to Evaluate the Technical Condition and Function of Extraction Wells

The declining supply of available groundwater resources is increasing the importance of extraction wells. To maximize the yield of extraction wells, the operators do not always respect the sustainable use of groundwater resources. These efforts can affect water quality and impact the service life of an extraction well, mainly through the clogging process. As part of the INV-FLOW project, an apparatus for evaluating the functionality of an extraction well by measuring the vertical water flow through its screen and filter was designed and tested. The apparatus consists of two electromagnetic induction flowmeters, two pneumatic seals, and a pump with the possibility of regulation. After an initial laboratory verification of the fundamental concept, the apparatus was successfully tested in real conditions. Two extraction wells, HJ-3 and HJ-4, intended for water supply to an agricultural production plant, were measured at a pilot site in the Czech Republic using the INV-FLOW apparatus. Although the HJ-3 extraction well is at the end of its service life, the HJ-4 extraction well is a newly installed well. In the new extraction well, HJ-4, a high proportion of water flowing through the gravel pack relative to the total pumping flow (93–97%) was measured using the INV-FLOW apparatus at different pumping rates. In the case of the HJ-3 extraction well, screen and filter clogging contributed significantly to the limited water flow through the gravel pack. In the most affected parts of the extraction well (15–20 m b.g.l.), the proportion of water flowing through the gravel pack relative to the total pumping flow ranged from 10 to 20%. The pilot tests confirmed the functionality of the apparatus and the possibility of using it to evaluate the degree of clogging and incrustation of an extraction well. The pilot tests thus demonstrated the usability of the INV-FLOW apparatus. The extraction well operator can assess the level of clogging or incrustation of the extraction well and decide on the need for the rehabilitation of an extraction well, or the termination of its operation.

Redesign Model Instalasi Pipa Saluran Air Bersih Di Desa Toniku Jailolo Selatan

The purpose of the service program to redesign the installation of clean water pipelines is to provide new installations and repair clean water distribution pumps that are able to distribute clean water originating from river water in the Toniku Village area so that the water distribution system runs more evenly, both to the reservoir and to the reservoir. the community directly. The implementation of the activity begins with an initial survey to see the condition of the artificial wells and water reservoirs that will be repaired where there are artificial wells installed on the banks of the river. Repairs to the pipe installation are carried out by replacing 2 4-inch pipes so that the flow of water that will enter the reservoir does not suffer losses or is wasted. The initial design before the change was that there were many pipe connections that were installed from the pump to the reservoir so that the water flowing into the reservoir experienced a lot of loss or wasted a lot. From the results of the field review, the electrical capacity to drive the pump is not sufficient because the type of electrical cable connected is not suitable or unable to drive the two pumps. Errors also occur in the installation of capacitors where the pump has a 40 F capacitor type but the one installed is 50 F. For the problem of electricity capacity, the village government has tried to coordinate with PLN to replace the power cable. As for the capacitor problem, in this program we bought 2 capacitors to be replaced and installed. Keywords: Redesign, Water Pump, Reservoir, Drain Installation

The evaluation of the efficiency of horizontal wells

The number of fields that have reached stage IV of development is increasing every year. Due to the high level of water cut, it becomes difficult to develop residual recoverable reserves. Also, due to the increase in the share of high-viscosity oils in Kazakhstan, the task of their effective development becomes more complicated. The development of terrigenous reservoirs, which have a complex structure and contain high-viscosity oil, is usually characterized by low production rates and oil recovery factors. Currently, technologies that ensure high efficiency in the development of such deposits are very expensive.
 In this regard, the development of oil fields through the commissioning of horizontal wells is becoming more in demand, capable of increasing the efficiency of developing oil reserves. Drilling of horizontal wells is considered for:
 
 floating reservoirs with low reservoir production coverage due to high water cut. High levels of water cut are due to breakthroughs of bottom water and degraded technical condition of wells (annular flows, wear and leakage of the string, depressurization of previously isolated intervals and poor quality of cement adhesion);
 thin layers, not involved in the production. Basically, thin layers are not involved in the production due to the low performance of vertical wells;
 on horizons with high-viscosity oil. In highly viscous horizons, the injected water breaks through to the bottom of production wells along the base of the reservoir when the horizon is not developed.
 
 Also in the Atyrau region, fields with hard-to-recover reserves (fields with high oil viscosity and low permeability of the productive horizon) are being developed. It is in such fields that horizontal wells have already been drilled and will be drilled in the future.
 The presented article discusses the results of the analysis of the drilled horizontal wells in the North Volga and Aknur oil fields.

Integrating the Geology, Seismic Attributes, and Production of Reservoirs to Adjust Interwell Areas

Abstract —Dynamic models of the seismic, geological, and flow characteristics of a reservoir are the main tool used to evaluate the potential of drilling new infill wells. Static geological models are mainly based on borehole data combined with dynamic analyses of production dynamics. They are used to determine the redevelopment of and adjustments to new drilling locations; however, such models rarely incorporate seismic data. Consequently, it is difficult to control the changes in geological models between wells, which results in the configuration of well positions and predicted results being less than ideal. To improve the development of adjusted areas in terms of their remaining oil contents, we developed a new integrated analysis that combines static sediment modelling, including microfacies analysis (among other reservoir and seismic properties), with production behaviours. Here, we illustrate this new process by (1) establishing favourable areas for static geological analysis; (2) studying well recompletion potential and the condition of non-producing wells; (3) conducting interwell analyses with seismic and sedimentary data; (4) identifying potential sites constrained by seismic and geological studies, as well as initial oilfield production; (5) providing suggestions in a new well development plan.

Uncertainty Evaluation Method and Application of Reservoir Lithofacies Proportion under the Condition of Few Wells

Abstract The proportion of different lithofacies is essential to determine the net-gross ratio, which directly affects the calculation of oil and gas reserves. Under the condition of few wells, the reliability of different lithofacies proportions obtained using well data is poor because it is difficult to estimate the uncertainty variation range of different lithofacies proportions. The present study overcomes this problem using an uncertainty evaluation method for reservoir lithofacies proportion. First, different lithofacies proportions of the reservoir are determined using the well and seismic data and are considered as the most likely estimated. Based on the lithofacies proportion, the lithofacies models of the study area are developed. Second, uniform and random methods are applied to sample the lithofacies models, and then, the probability distribution functions of different lithofacies proportions are derived. Third, the three levels of lithofacies proportions in the study area are calculated using the method of quantile and discretization of the probability distribution. Finally, we take M gas field as a sample and compare the test results of the fixed and random well structures. The results show that the sampling results of the fixed well structure model significantly deviate under the influence of the extension direction of the channel and well pattern distribution. Therefore, it is suggested to use random well structure to determine the uncertainty distribution range of lithofacies proportion.

CONSEQUENCES OF ELECTROMAGNETIC DEFECTOSCOPY IN OIL AND GAS WELLS

Currently, various methods and methods are used to diagnose the technical condition of wells, which make it possible to determine the most complete and reliable picture of its condition. This paper presents the results of assessing the technical condition of oil wells using the electromagnetic flaw detection method. Keywords: oil and gas wells, diagnostics of technical condition, electromagnetic flaw detection, corrosion of the wall of the pipe column.

Understanding Slovakian Gas Well Performance and Capability through ArcGIS System Mapping

There are two important territories in Slovakia with functioning gas well operations: the Eastern Slovak Lowland and the Vienna Basin. This article focuses on the creation of electronic monitoring and graphical mapping of the current technical conditions of gas wells in the Eastern Slovak Lowland. An analysis of the gas wells’ current state in the terrain is available. The aim of the article is to draw attention to the current state of gas wells, such as the insufficient processing of gas wells, the lack of summary and uniform records concerning them, and the lack of an electronic system for monitoring the technical security of the wells. The scientific contribution of this article lies in its ability to interpret and address operational problems related to gas wells. Through analogy, the step algorithm expresses the possibility of also using gas wells for oil, geothermal and hydrogeological wells. The intention was to highlight the importance of the need to create a database for the security and strategic needs of the state regarding the storage of natural gas. As of yet, no computer or graphic system has been used in Slovakia to monitor, unify and clarify the actual technical condition of gas wells. Using the ArcGIS electronic and graphical software tool, the mapping and recording of gas wells was carried out in the area under investigation. The mapping was completed with the mentioned technical patterns. These patterns have the information found on individual gas wells. After the information is added to the database, this mapping can also be carried out in another important area with functioning gas wells, such as in the Vienna Basin, which could be another theme for further research in this area.

Silica sand enhanced cement mortar for cementing steam injection well up to 380 °C

In this study, an ultra-high temperature of 380 °C was used to simulate the high-temperature condition of steam injection wells. The silica sand with different particle sizes was applied to prepare the silica-enhanced cement with various Ca/Si ratios. The compressive strength, hydration products, and microstructure of silica-enhanced cement were evaluated to probe the influence of high-temperature steam curing (from 50 to 380 °C), silica particle size (from 150 to 500 mesh), and Ca/Si ratio (from 0.7 to 1.44) on the performance of cement. The corresponding mechanism was also revealed. Test results show that the particle size of silica influences the compressive strength of cement mainly by changing the mineral composition in cement matrix, rather than altering the microstructure of cement. The Ca/Si ratio affects the compressive strength of silica-enhanced cement by controlling both hydration products and micropore structure of cement. Based on the experimental results, a silica-enhanced cement system was proposed. The rheology, thickening and fluid loss properties of cement slurry were evaluated, and proved to be suitable in cementing the steam injection wells. The proposed cement system shows an excellent compressive strength of more than 50 MPa even under 7th-round of steam curing conditions.

Application of polymer compositions in repair and insulation works in wells

The state of Russia's resource base has a downward trend. In the light of the need to keep the economic indicators not lower than the achieved ones, the emerging problems in the production of hydrocarbons require to solve them are use of new methods. Reducing the volume of associated water, maintaining the environmental safety of oil production while maintaining and even reducing the cost of oil production, due to new technologies and materials, are urgent tasks. For issues of reliable restoration of the technical condition of wells and the limitation of water inflow are this work is devoted. The technology based on the use of a modified polymer water-insulating composition is presented. Analytical and field studies were conducted. The technology and the polymer composition have shown the possibility of application during water inflow restriction and repair and insulation works. Keywords: repair and insulation works; water shutoff; polymer composition; modification of the composition

Review of directional drilling design and operation of geothermal wells in Indonesia

Generally, geothermal fields in Indonesia are situated in the mountains, forests, and remote area. The surface area, access, environment, license, and permit are limited, so that from a permitted well pad many wells are designed directionally to reach the reservoir.Directional drilling in geothermal wells is challenging due to hard volcanic rocks, the presence of vugs or cavern, and high temperatures leading to massive lost circulation, drilling break, and the difficulty to turn and control the direction stably during drilling. These cause a critical condition reducing the wellbore quality: high Dogleg Severity (DLS), tight hole, and stuck pipe occurrence. Besides, this leads to higher stress and strain experienced by the casing or liner and causes yield strength reduction and failure.Thus, it is essential that the directional drilling design and operation, particularly trajectory, be optimized. This research summarized methods to evaluate the actual drilling operation and wellbore condition of wells in Dieng Field. The result is useful to identify the critical conditions caused by drilling and formation problems setting the maximum load limitations of the design and subsequent operation. It is recommended that buckling analysis, full-scale testing, and several design and operation scenarios be conducted prior to the drilling operation.

The Implementation of Flow Performance Test to Monitor Well Performance in Geothermal Field

Reservoir monitoring of a geothermal field has an important role in determining the direction of company policies in managing a geothermal field, one of which needs to be monitored is by looking at changes in the pattern of the deliverability curve so that it can determine changes in the characteristics and performance of production wells. In order to update the deliverability curve, it is necessary to conduct periodic production tests. However, this cannot be done due to limited steam reserves. This research was conducted to determine the performance of production wells using the Flow Performance Test (FPT) method. This method is an alternative solution that can update the production well deliverability curve without leaving the gathering system. The FPT is applied to UBL-DL5 and JL2, UBL-JL3 is shown to validate the equations used. The data obtained were validated with TFT data and production test data where the deviation of the data obtained for UBL-DL5 was 1.42%, UBL-JL2 was 2.7%, and UBL-JL3 was 2.74%. The comparison of the UBL-DL5 and JL3 models based on time shows a significant production decline, and this is possible because the wells have only been operating within a period of 4 months – 1 year where the condition of production wells are still looking for stable condition, while the UBL-JL2 have not been seen there is a change in characteristic. The FPT is reliable enough to be used as an alternative method in monitoring production wells compared to the TFT method and the horizontal lip pressure production test. The FPT program should be conducted periodically and synchronized with the company’s operational activities plan. The delivery curve modeling as FPT result is used to monitor production wells’ condition as the basis for the company to develop a dynamic five-year work plan.