Unlock Condensate Reserves by Peripheral Development of Giant Condensate

This paper addresses the development of peripheral area in order to maximize the condensate production in a giant Recycle Gas-Condensate Reservoir in UAE. The condensate reservoir is producing many years under recycling mode to maintain the pressure and maximize the gas condensate recovery. The producers and injector wells are in a line drive pattern where the injected fluid is lean gas to maintain 100% VRR. The condensate production declined through the years due to gradual pressure decrease as well as injected lean gas/N2 breakthrough. Several studies were done to increase condensate recovery and extend gas production plateau. The methodology adopted for this study is the developing of the peripheral area in the giant recycle reservoir as part of its full field development plan (FFDP) in order to provide more pressure support initially and to increase the sweep efficiency for more condensate recovery. In addition; it is worth to mention that peripheral wells will provide production relaxation from some gas produces which have lean gas and N2 breakthroughs. Pilot wells were drilled to examine and confirm the strategy assumed by analyzing the performance of those wells in terms of location, condensate production, CGR values and trajectory. Simulation modeling was as well used for matching purposes and future prediction and forecasting. Pilot wells were drilled in deferent peripheral area in the reservoir and completed as horizontal gas producers. By analyzing the current wells performance it has been approved that the wells are producing high condensate about (2000-2500) MMstb and producing high CGR values about (80-100). Simulation modeling were utilize for future prediction and confirmed that the development of peripheral area by drilling additional wells enhances the sweeping efficiency and participated in expected gain a multimillions of barrels of additional condensate with maintaining the same business plan gas production target. It was promising to have more incremental in case of ramping up the production. The paper discussed in detail about methodology adopted in order to unlock the condensate reserves by peripheral development and confirmed the results of the gain of condensate production and CGR from actual data and simulation modeling. The provided information is quite informative to be widely used and applied in similar reservoirs.

Maximizing Condensate Production Opportunities in a Giant Stacked Reservoir-Case Study

This paper addresses the opportunities of maximizing the condensate production in a giant Recycle Gas-Condensate Reservoir in UAE. The condensate reservoir is producing many years under recycling mode to maintain the pressure and maximize the gas condensate recovery. The producers and injector wells are in a line drive pattern where the injected fluid is lean gas to maintain 100% VRR. The condensate production declined through the years due to gradual pressure decrease as well as injected lean gas/N2 breakthrough. Several studies were done to increase condensate recovery and extend gas production plateau.

Progress on Modeling of Dynamic Productivity of Fractured Gas Condensate Reservoir Based on a Fluid-Solid Coupling Method

Bozhong 19-6 gas field is the first discovered large-scale gas condensate field in eastern China, which is also one of the largest metamorphic rock gas condensate fields in the world. It is a buried hill type, low permeability reservoir, with ultra-high condensate content where the fluid is nearly at its dew point pressure. No similar experience with such reservoirs have previously been reported in the context of gas field development in China and step-by-step progresses is been made to characterize this reservoir. Overall, documentation concerning this type of reservoir is rarely seen worldwide. This paper includes key successful results from multiple perspectives including experiments correlations, numerical modeling and the significance of incorporating certain details. Based on a fluid-solid coupling method, the simulations consider several factors including the fracture distribution, low permeability, medium deformation, and condensate characteristics, as well as their effects on the gas productivity. In the laboratory experiments, the stress sensitivity of the rock was tested using representative core samples. Here, experiment-based correlations of the starting pressure gradient of the gas condensate reservoir are proposed. The starting pressure gradient of different fluid types, such as black oil and gas condensate are highlighted as accurately simulating the reservoir. As a result, the numerical model to predict the dynamic productivity of a single well was successfully established considering all those factors. This paper can serve as a reference for studying other studies of metamorphic, fractured gas condensate reservoirs.

The problem of adapting the gas-condensate reservoir model under conditions of a low volume and low reliability of the initial data

The article is dedicated to the problem of adapting the hydrodynamic model of a gas-condensate reservoir with a low volume and low reliability of the field and laboratory data. The purpose of the work is a qualitative reservoir development forecast. All available formation fluid downhole samples were studied. The authors analyzed water samples taken during the reservoir development process. The monthly production reports data and the gas-condensate well testing installation measurements were used in the article. The authors carried out the hydrodynamic model multivariate calculations in order to mathematically repeat historical waterflooding. An approach to the retrospective analysis of the production and laboratory data is shown in order to remove uncertainties in the reservoir and production engineering. The work performed made it possible to determine the most probable content of C5+ components in the reservoir gas, as well as to assess the risk of the future formation water invasion into the reservoir. As a result of this work, it was recommended to exclude two edge wells in order to reduce the gas well waterflooding. In addition, the authors calculated an improved reservoir development variant. They proposed to transfer a part of gas wells to water wells at the stage of declining production. This operation will reduce the reservoir water-flooding rate.

Methane and other Volatile HC Gasses in Produced-Water

Getting correct estimates for Volatile Organic Compounds (VOCs) and greenhouse gases (GHGs) from water storage tanks is not only important for maintaining emission compliance for state and national regulatory authorities, but also crucial in designing the capital-intensive systems for economic use of methane and other Natural Gas Liquid (NGL) gasses. This paper highlights the significance of gas liberated from produced water tanks in the fields. The paper presents a laboratory method to estimate such emissions from produced-water storage tanks by virtue of the in-situ water getting depressurized and releasing VOCs, and other emission gasses such as Hydrogen Sulfide (H2S) and Carbon Dioxide (CO2). Further, the paper provides qualitative and quantitative assessment of the gas liberated from produced-water by analyzing the gas liberated from produced-water from gas-condensate reservoir wells from the Marcellus region.

Continuous Improvement in Well Delivery

The Bulla gas-condensate reservoir is located in the north-west side of Baku Archipelago, is one of the most complex high-pressure fields in the world, with close PPFG margins and reactive clay in the overburden. The objective of this paper is to share the experience of how the challenges in the overburden section are managed to achieve improvement in the well delivery, through the application of continuous learning approach and the use of new technologies. The Bulla wells are highly complex wells in the region. The overburden shales are young sediments 250 to 1200 m to be drilled and cased off with 24" casing, this has significant challenges such as slow ROP, Bit Balling and tight hole due to the shale swelling. These challenges can lead to issues such as stuck pipe and lack of zonal isolation. To overcome the challenges and similar cases in well delivery, continuous improvement (CI) techniques and new technologies were evaluated and applied in the project. The CI approach helped identify the issues in the delivery of the overburden and actions taken resulted in significant improvement in well delivery and reduced the risks. The issues were worked on, and most feasible solution was chosen. The improvement plan has been risk assessed for the challenges of handling large volumes, possible losses, spillage etc. and risk control actions are implemented. The next well was drilled with higher operational efficiency, cost optimization and better hole quality to achieve zonal isolation by proper placement of cement. Further improvements were planned for the next wells in the field, by extending under reaming range through the application of new technologies. For 18 5/8" casing, a hole size of 24" required, this was drilled using multiple trips due to tool limitations. By using the advanced drilling dynamics software, BHA along with the required under reamer identified tools and design the section was delivered in one run. The application of this approach will not only reduce the time and cost but will also will help to deliver a quality well bore. The study provides an overview of how CI can be effectively implemented to achieve the overall improvement in the performance of the well delivery. Additionally, it gives insight on how new technologies in BHA design and reaming can improve the drilling performance.

Condensate banking removal: study on ultrasonic amplitude effect

Hydrocarbons in a gas condensate reservoir consist of a wide variety of molecules which will react varyingly with the change of pressure inside the reservoir and wellbore. The presence of heavier ended hydrocarbons such as C5 and above, condensate banking will occur as pressure depletes. Pressure drop below dew point pressure causes condensate buildup which will give a negative impact in the productivity index of a gas condensate reservoir. Gas condensate reservoirs experience liquid drop out when pressure depletion reaches below dew point pressure. This occurrence will eventually cause condensate banking over time of production where condensate builds up in pore spaces of near-wellbore formations. Due to increase in condensate saturation, gas mobility is reduced and causes reduction of recoverable hydrocarbons. Instead of remediating production loss by using unsustainable recovery techniques, sonication is used to assist the natural flow of a gas condensate reservoir. This study aims to evaluate the effects of various ultrasonic amplitudes on condensate removal in a heterogenous glass pack in flowing conditions with varying exposure durations. Experiments were conducted by using n-Decane and a glass pack to represent condensate banking and near-wellbore area. Carbon dioxide was flowed through the pack to represent flowing gas from the reservoir after sonication of 10%, 50% and 100% amplitudes (20 kHz and 20 Watts). Analysis of results shows recovery of up to 17.36% and an areal sweep efficiency increase in 24.33% after sonication of 100% amplitude for 120 min due to reduction in viscosity. It was concluded that sweeping efficiency and reciprocal mobility ratio are increased with sonication of 100% amplitude for 120 min. This indicates that mobility of n-Decane is improved after sonication to allow higher hydrocarbon liquid production. Insights into the aspects of the mechanical wave are expected to contribute to a better understanding of tuning the sonic wave, to deliver remarkable results in a closed solid and fluid system. This form of IOR has not only proved to be an effective method to increase productivity in gas condensate wells, but it is also an environmentally sustainable and cost-effective method.

Influence of geological reservoir heterogeneity on exploitation conditions of Garadagh field / underground gas storage (Azerbaijan)

Underground oil and gas reservoirs (formations) are characterized by spatial variability of their structure, material composition and petrophysical properties of its constituent rocks: particle size distribution, porosity, permeability, structure and texture of the pore space, carbonate content, electrical resistivity, oil and water saturation and other properties. When assessing development and exploitation conditions for underground gas storages, created in depleted underground oil and gas reservoirs, the inherited nature of the reservoir development should be taken into account. Therefore, identifying the features of variations in well productivity is a crucial task, solution of which can contribute to the creation of more efficient system for underground gas storage exploitation. The paper presents the findings of comparative analysis of spatial variations in well productivity during the exploitation of the Garadagh underground gas storage (Azerbaijan), created in the depleted gas condensate reservoir. An uneven nature of the variations in well productivity was established, which was connected with the reservoir heterogeneity (variations in the reservoir lithological composition and poroperm properties). The research was based on the analysis of spatial variations of a number of reservoir parameters: the reservoir net thickness, lithological composition and poroperm properties. The analysis of variations in the net thickness and poroperm properties of the VII horizon of the Garadagh gas condensate field was carried out based on the data of geophysical logging of about 40 wells and studying more than 90 core samples. The data on of more than 90 wells formed the basis for the spacial productivity variation analysis. The analysis of productivity variation in the space of well technological characteristics (based on data from 18 wells) in the Garadagh underground gas storage (UGS) was carried out through the example of the volume of cyclic gas injection and withdrawal in 2020–2021 season. The studies allowed revealing non-uniform spacial variations in the volumes of injected and withdrawn gas at the Garadagh UGS, created in the corresponding depleted gas condensate reservoir. The features of the UGS exploitation conditions are in good agreement with the features of the reservoir development conditions (variations in the well productivity). The inherited nature of the reservoir development and the underground gas storage exploitation is substantiated by the reservoir heterogeneity caused by the spatial variability of the reservoir lithological composition and poroperm properties. Assessing and taking into account the reservoir heterogeneity when designing underground gas storage exploitation conditions should be an important prerequisite for increasing UGS exploitation efficiency.