SPE Middle East Artificial Lift Conference and Exhibition
Artificial lift systems (ALS) should be thoroughly analyzed to minimize non-productive time, incr... more Artificial lift systems (ALS) should be thoroughly analyzed to minimize non-productive time, increase production and reserves, reduce cost and failure, and maximize capital efficiency. This work proposes a novel systematic for ALS analysis approach that implements data analytics for historical performance tracking and benchmarking, heuristic diagnostics for suboptimal identification, and reliable model-based solutions for opportunity evaluation. The proposed methodology follows the principles of integrated reservoir management and greatly reduces the time to manage ALS systems by combining expert knowledge, data analysis with model-based calculation in pursuit of extreme efficiency and high accuracy. Our efficient workflow builds from intelligent data pre-processing capabilities, which facilitate fast and structured analysis of complex datasets. The metrics and scoreboard are intuitive, comprehensive and unique, and are scarcely documented in technical literature. These evaluations ...
High-pressure and high-temperature (HPHT) gas reservoirs are defined as having pressures greater ... more High-pressure and high-temperature (HPHT) gas reservoirs are defined as having pressures greater than 10,000 psia and temperatures over 300ºF. Modeling the performance of these unconventional reservoirs requires the understanding of gas behavior at elevated pressure and temperature. An important fluid property is gas viscosity, as it is used to model the gas mobility in the reservoir that can have a significant impact on reserves estimation during field development planning. Accurate measurements of gas viscosity at HPHT conditions are both extremely difficult and expensive. Thus, this fluid property is typically estimated from published correlations that are based on laboratory data. Unfortunately, the correlations available today do not have a sufficiently broad range of applicability in terms of pressure and temperature, and so their accuracy may be doubtful for the prediction of gas viscosity at HPHT conditions. This paper reviews the databases of hydrocarbon gas viscosity that are available in the public domain, and discusses the validity of published gas viscosity correlations based on their applicability range.
A practical method for measuring gas viscosity uses gas to calibrate the rolling ball viscometer ... more A practical method for measuring gas viscosity uses gas to calibrate the rolling ball viscometer over the whole interest range of pressure and temperature. It reduces the turbulent effect of gas flow around the ball. The viscometer calibration at only atmospheric pressure yields poor results, because it cannot accommodate the turbulent effect at higher pressures. We used nitrogen to calibrate the viscometer for the pressure up to 8,000 psia and temperature up to 260°F. Optimal tube inclination angle and also ball/tube diameter ratio ensure the laminar flow around the ball and improve the accuracy of the results. Viscosity measurements of ultrapure CO 2 confirmed this technique.
Measured gas viscosity data at high pressures and high temperatures indicates that the most commo... more Measured gas viscosity data at high pressures and high temperatures indicates that the most common gas viscosity correlations return up to 9% relative error in cumulative gas recovery factor at extreme conditions, which translates to significant economic error in current giant natural gas reservoirs.
Gas viscosity is an important fluid property in petroleum engineering due to its impact in oil an... more Gas viscosity is an important fluid property in petroleum engineering due to its impact in oil and gas production and transportation where it contributes to the resistance to the flow of a fluid both in porous media and pipes. Although the property has been studied thoroughly at low to intermediate pressures and temperatures, there is lack of detailed knowledge of gas viscosity behavior at high pressures and high temperatures (HPHT) in the oil and gas industry. The need to understand and be able to predict gas viscosity at HPHT has become increasingly important as exploration and production has moved to ever deeper formations where HPHT conditions are more likely to be encountered. Knowledge of gas viscosity is required for fundamental petroleum engineering calculations that allow one to optimize the overall management of a HPHT gas field and to better estimate reserves. Existing gas viscosity correlations are derived using measured data at low to moderate pressures and temperatures, i.e. less than 10,000 psia and 300 o F, and then extrapolated to HPHT conditions. No measured gas viscosities at HPHT are currently available, and so the validity of this extrapolation approach is doubtful due to the lack of experimental calibration. The falling body viscometer is selected to measure gas viscosity for a pressure range of 3,000 to 24,500 psia and temperature range of 100 to 415 o F. Nitrogen was used to calibrate the instrument and to account for the fact that the concentrations of non-hydrocarbons are observed to increase dramatically in HPHT reservoirs. Then methane viscosity is measured to reflect the fact that, at HPHT conditions, the reservoir fluids will be very lean gases, typically methane with some degree of impurity. The experiments showed that while the correlation of Lee et al. accurately estimates gas viscosity at low to moderate pressure and temperature, it does not provide a good match to gas viscosity at HPHT conditions.
Pressure transient analysis (PTA) is typically performed on pressure BU data acquired over a peri... more Pressure transient analysis (PTA) is typically performed on pressure BU data acquired over a period from a few hours to a few days, while production data analysis (PDA) is performed with production data acquired over a period of a few days to several years. Recent approaches to extending a pressure BU response by deconvolving production data seem promising, but simple rate-normalized pressure (RNP) and its derivative may be more straightforward provided redundant data and artifacts are eliminated in the RNP processing.
Many benefits by use of Oil-Based Mud (OBM) in drilling oil and gas wells have been identified in... more Many benefits by use of Oil-Based Mud (OBM) in drilling oil and gas wells have been identified in the oil industries worldwide. However the current ever increasing environmental legislations in preventing OBM application in the industries have dictated the use of water-based drilling fluid as the most environmentally acceptable alternative. On the other hand, drilling with water-based systems in shaly formations may cause many problems such as wellbore instability and high torque and drag. Therefore the most optimum alternatives would be different kinds of inhibited water-based systems in which adverse effects of shaly formations can also be controlled. These water-based alternatives are called High-Performance Water-Based Mud (HPWBM). Also the OBM properties is the final goal of the researchers to reach in their investigations to design a suitable HPWBM since OBM is the ideal drilling fluid to drill problematic formations.
Viscosity is one of the gas properties that is always uncertain at high-pressure and high-tempera... more Viscosity is one of the gas properties that is always uncertain at high-pressure and high-temperature (HPHT) conditions because no reliable correlation has been developed for HPHT and accurate measurement of gas viscosities at HPHT is difficult. However, the industry currently does not pay sufficient attention to the need for accurate gas viscosity values in HPHT gas fields' development.
High-pressure/high-temperature (HP/ HT) gas reservoirs have pressures greater than 10,000 psia an... more High-pressure/high-temperature (HP/ HT) gas reservoirs have pressures greater than 10,000 psia and temperatures higher than 300°F. Modeling the performance of these reservoirs requires understanding gas behavior at elevated pressure and temperature. Gas viscosity is used to model the gas mobility in the reservoir and can have a significant effect on reserves estimation during field-development planning. Accurate measurements of gas viscosity at HP/HT conditions are extremely difficult. Public-domain databases of hydrocarbon-gas viscosity were reviewed for validity of gas-viscosity correlations and their applicability range.
SPE Middle East Artificial Lift Conference and Exhibition
Artificial lift systems (ALS) should be thoroughly analyzed to minimize non-productive time, incr... more Artificial lift systems (ALS) should be thoroughly analyzed to minimize non-productive time, increase production and reserves, reduce cost and failure, and maximize capital efficiency. This work proposes a novel systematic for ALS analysis approach that implements data analytics for historical performance tracking and benchmarking, heuristic diagnostics for suboptimal identification, and reliable model-based solutions for opportunity evaluation. The proposed methodology follows the principles of integrated reservoir management and greatly reduces the time to manage ALS systems by combining expert knowledge, data analysis with model-based calculation in pursuit of extreme efficiency and high accuracy. Our efficient workflow builds from intelligent data pre-processing capabilities, which facilitate fast and structured analysis of complex datasets. The metrics and scoreboard are intuitive, comprehensive and unique, and are scarcely documented in technical literature. These evaluations ...
High-pressure and high-temperature (HPHT) gas reservoirs are defined as having pressures greater ... more High-pressure and high-temperature (HPHT) gas reservoirs are defined as having pressures greater than 10,000 psia and temperatures over 300ºF. Modeling the performance of these unconventional reservoirs requires the understanding of gas behavior at elevated pressure and temperature. An important fluid property is gas viscosity, as it is used to model the gas mobility in the reservoir that can have a significant impact on reserves estimation during field development planning. Accurate measurements of gas viscosity at HPHT conditions are both extremely difficult and expensive. Thus, this fluid property is typically estimated from published correlations that are based on laboratory data. Unfortunately, the correlations available today do not have a sufficiently broad range of applicability in terms of pressure and temperature, and so their accuracy may be doubtful for the prediction of gas viscosity at HPHT conditions. This paper reviews the databases of hydrocarbon gas viscosity that are available in the public domain, and discusses the validity of published gas viscosity correlations based on their applicability range.
A practical method for measuring gas viscosity uses gas to calibrate the rolling ball viscometer ... more A practical method for measuring gas viscosity uses gas to calibrate the rolling ball viscometer over the whole interest range of pressure and temperature. It reduces the turbulent effect of gas flow around the ball. The viscometer calibration at only atmospheric pressure yields poor results, because it cannot accommodate the turbulent effect at higher pressures. We used nitrogen to calibrate the viscometer for the pressure up to 8,000 psia and temperature up to 260°F. Optimal tube inclination angle and also ball/tube diameter ratio ensure the laminar flow around the ball and improve the accuracy of the results. Viscosity measurements of ultrapure CO 2 confirmed this technique.
Measured gas viscosity data at high pressures and high temperatures indicates that the most commo... more Measured gas viscosity data at high pressures and high temperatures indicates that the most common gas viscosity correlations return up to 9% relative error in cumulative gas recovery factor at extreme conditions, which translates to significant economic error in current giant natural gas reservoirs.
Gas viscosity is an important fluid property in petroleum engineering due to its impact in oil an... more Gas viscosity is an important fluid property in petroleum engineering due to its impact in oil and gas production and transportation where it contributes to the resistance to the flow of a fluid both in porous media and pipes. Although the property has been studied thoroughly at low to intermediate pressures and temperatures, there is lack of detailed knowledge of gas viscosity behavior at high pressures and high temperatures (HPHT) in the oil and gas industry. The need to understand and be able to predict gas viscosity at HPHT has become increasingly important as exploration and production has moved to ever deeper formations where HPHT conditions are more likely to be encountered. Knowledge of gas viscosity is required for fundamental petroleum engineering calculations that allow one to optimize the overall management of a HPHT gas field and to better estimate reserves. Existing gas viscosity correlations are derived using measured data at low to moderate pressures and temperatures, i.e. less than 10,000 psia and 300 o F, and then extrapolated to HPHT conditions. No measured gas viscosities at HPHT are currently available, and so the validity of this extrapolation approach is doubtful due to the lack of experimental calibration. The falling body viscometer is selected to measure gas viscosity for a pressure range of 3,000 to 24,500 psia and temperature range of 100 to 415 o F. Nitrogen was used to calibrate the instrument and to account for the fact that the concentrations of non-hydrocarbons are observed to increase dramatically in HPHT reservoirs. Then methane viscosity is measured to reflect the fact that, at HPHT conditions, the reservoir fluids will be very lean gases, typically methane with some degree of impurity. The experiments showed that while the correlation of Lee et al. accurately estimates gas viscosity at low to moderate pressure and temperature, it does not provide a good match to gas viscosity at HPHT conditions.
Pressure transient analysis (PTA) is typically performed on pressure BU data acquired over a peri... more Pressure transient analysis (PTA) is typically performed on pressure BU data acquired over a period from a few hours to a few days, while production data analysis (PDA) is performed with production data acquired over a period of a few days to several years. Recent approaches to extending a pressure BU response by deconvolving production data seem promising, but simple rate-normalized pressure (RNP) and its derivative may be more straightforward provided redundant data and artifacts are eliminated in the RNP processing.
Many benefits by use of Oil-Based Mud (OBM) in drilling oil and gas wells have been identified in... more Many benefits by use of Oil-Based Mud (OBM) in drilling oil and gas wells have been identified in the oil industries worldwide. However the current ever increasing environmental legislations in preventing OBM application in the industries have dictated the use of water-based drilling fluid as the most environmentally acceptable alternative. On the other hand, drilling with water-based systems in shaly formations may cause many problems such as wellbore instability and high torque and drag. Therefore the most optimum alternatives would be different kinds of inhibited water-based systems in which adverse effects of shaly formations can also be controlled. These water-based alternatives are called High-Performance Water-Based Mud (HPWBM). Also the OBM properties is the final goal of the researchers to reach in their investigations to design a suitable HPWBM since OBM is the ideal drilling fluid to drill problematic formations.
Viscosity is one of the gas properties that is always uncertain at high-pressure and high-tempera... more Viscosity is one of the gas properties that is always uncertain at high-pressure and high-temperature (HPHT) conditions because no reliable correlation has been developed for HPHT and accurate measurement of gas viscosities at HPHT is difficult. However, the industry currently does not pay sufficient attention to the need for accurate gas viscosity values in HPHT gas fields' development.
High-pressure/high-temperature (HP/ HT) gas reservoirs have pressures greater than 10,000 psia an... more High-pressure/high-temperature (HP/ HT) gas reservoirs have pressures greater than 10,000 psia and temperatures higher than 300°F. Modeling the performance of these reservoirs requires understanding gas behavior at elevated pressure and temperature. Gas viscosity is used to model the gas mobility in the reservoir and can have a significant effect on reserves estimation during field-development planning. Accurate measurements of gas viscosity at HP/HT conditions are extremely difficult. Public-domain databases of hydrocarbon-gas viscosity were reviewed for validity of gas-viscosity correlations and their applicability range.
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Papers by Ehsan Davani