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Deli Gao - One of the best experts on this subject based on the ideXlab platform.
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assessment on the sustained Casing pressure scp with consideration of the infiltration of formation fluid into the annulus of deepwater wells
Journal of Petroleum Science and Engineering, 2020Co-Authors: Yanbin Wang, Jing Zeng, Deli GaoAbstract:Abstract The sustained Casing pressure (SCP) is a common problem in deepwater wells, which is caused by the coupling effects of temperature and pressure and brings about significant challenges to the wellbore integrity. In this paper, the analysis model of temperature distribution along the wellbore has been presented firstly based on the Casing program and the basic principle of heat transfer, which is adopted as the boundary condition and initial condition of the SCP model. In this model, the annular spaces of the oil tubing-Production Casing, Production Casing-intermediate Casing, intermediate Casing-surface Casing are named as annulus A, annulus B and annulus C, respectively. Secondly, the mechanical model and governing equation of the SCP have been established based on the thermal elastic mechanics with consideration of the formation fluid infiltration into the annulus. Then, the SCP and its maximum allowable value have been figured out by solving the governing equation through the iteration calculation approach. At last, a SCP relief tool has been proposed to improve the stress state of Casing string and its performance has been evaluated. On this basis, the parameter sensitivity analysis has been carried out, where the influence of yield, Production time, the comprehensive permeability of cement sheath, physical parameters of fluid in the annuli and the formation fluid infiltration on the SCP are discussed in detail. Analysis results show that the ranking order of temperature variation is annulus A, annulus B, annulus C, while the ranking order of the SCP is annulus B, annulus C, and annulus A. The SCP at wellhead increases approximately linearly with the yield and the thermal expansion coefficient of the fluid in annulus. At the initial stage of Production, the well temperature and SCP gradually increase with the time, and then remain constant with the Production going on. However, the time of the SCP reaching stable decreases with the comprehensive permeability of the cement sheath. In addition, the maximum allowable value of the SCP is mainly restricted by the collapse resistance of the Production Casing, which occurs under the circumstance of annulus A is tunneled. The relief tool can significantly reduce the SCP in annulus B and C with about 30% of the reduction rate, which plays a positive role in improving the mechanical state of the Casing. This paper has reference significance for prediction of the SCP and evaluation of the well integrity of deepwater wells.
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prediction of sustained Production Casing pressure and Casing design for shale gas horizontal wells
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Fei Yin, Deli GaoAbstract:Abstract Casing failure in shale gas horizontal wells hinders the efficient development of shale gas. The sustained Casing pressure is the main failure mechanism, while the current analytic methods are not fit to shale gas horizontal wells. Hydraulic fracturing causes well temperature change, so the temperature distribution of horizontal well section is calculated based on heat transfer theory. According to thermoelasticity, the formula of annular volume change under the synergy of temperature and pressure is deduced. By substituting the temperature distribution and annular volume change into the prediction model, the sustained Production Casing pressure in horizontal wells is obtained. For the work condition of Production Casings in shale gas horizontal wells, an improved method of Casing design is proposed. Results indicate that the horizontal well temperature increases with the distance increase from well axis in the pattern of line-parabola. The thermoelastic deformations of Production Casing and surrounding rock change the annular volume observably. The sustained Production Casing pressure displays a quadratic polynomial increase with well temperature. The hydraulic fracturing pressure and sustained Casing pressure should be involved to design the Production Casing in shale gas horizontal wells. The research provides the prediction method of sustained Production Casing pressure in horizontal wells. The proposed Casing design method for shale gas horizontal wells ensures well integrity.
Mikalsen, Ann Elin - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the primary cement operation on the Production Casing in the Ekofisk field and the Eldfisk field
University of Stavanger Norway, 2009Co-Authors: Mikalsen, Ann ElinAbstract:Master's thesis in Petroleum engineeringThe foremost goal of primary cementing is to provide zonal isolation in a well. Cementing of the Casing/liner set right above the reservoir on the Ekofisk and Eldfisk fields are associated with a lot of challenges. Depletion and water flooding of a reservoir makes drilling and cementing increasingly difficult. At the Ekofisk and Eldfisk fields, the operational window above the reservoir is very narrow and difficult to predict due to the regression of fracture pressure the last 200 ft above the reservoir. This coupled with the natural faults and fractures in this area makes lost circulation a hindrance to provide zonal isolation. Cement history on the two fields shows that there is a very low chance of achieving required Casing cement isolation. Historical practices within the last two years have been analysed trying to find the root causes of any failure to meet the company requirements. A review of potential solutions to solve the issue has been presented. Different studies have been made, including hydraulic simulations, to come up with suggestions on how to reach the cement target for the two fields. In addition, simulations on how to cement the entire Miocene section were performed. A study performed in WellPlanTM-Opticem revealed that there still exist some challenges before the cement design and real time jobs can be properly imported and analysed in the software. During the work lack of cement job data storage system was discovered. A new way of cement data storage was suggested and established. Collection and analyses of cement jobs during the last two years on the M-wells was performed in order to investigate if there was a trend between lost circulation and different parameters. No clear trend was found. Hydraulic simulations were performed to investigate how different parameters impact the equivalent circulating density. A colloidal light weight cement was utilized in the simulations. The main results from the simulations showed that; Warp OBM is superior to Versatec OBM system from a well cementing perspective, the expandable liner hanger imposed a very high ECD and the liner hanger dimensions needs to be taken into account in hydraulic simulations. The overall outcome of the simulations indicates a possible solution on how to cement back to the previous Casing shoe
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Evaluation of the primary cement operation on the Production Casing in the Ekofisk field and the Eldfisk field
University of Stavanger Norway, 2009Co-Authors: Mikalsen, Ann ElinAbstract:The foremost goal of primary cementing is to provide zonal isolation in a well. Cementing of the Casing/liner set right above the reservoir on the Ekofisk and Eldfisk fields are associated with a lot of challenges. Depletion and water flooding of a reservoir makes drilling and cementing increasingly difficult. At the Ekofisk and Eldfisk fields, the operational window above the reservoir is very narrow and difficult to predict due to the regression of fracture pressure the last 200 ft above the reservoir. This coupled with the natural faults and fractures in this area makes lost circulation a hindrance to provide zonal isolation. Cement history on the two fields shows that there is a very low chance of achieving required Casing cement isolation. Historical practices within the last two years have been analysed trying to find the root causes of any failure to meet the company requirements. A review of potential solutions to solve the issue has been presented. Different studies have been made, including hydraulic simulations, to come up with suggestions on how to reach the cement target for the two fields. In addition, simulations on how to cement the entire Miocene section were performed. A study performed in WellPlanTM-Opticem revealed that there still exist some challenges before the cement design and real time jobs can be properly imported and analysed in the software. During the work lack of cement job data storage system was discovered. A new way of cement data storage was suggested and established. Collection and analyses of cement jobs during the last two years on the M-wells was performed in order to investigate if there was a trend between lost circulation and different parameters. No clear trend was found. Hydraulic simulations were performed to investigate how different parameters impact the equivalent circulating density. A colloidal light weight cement was utilized in the simulations. The main results from the simulations showed that; Warp OBM is superior to Versatec OBM system from a well cementing perspective, the expandable liner hanger imposed a very high ECD and the liner hanger dimensions needs to be taken into account in hydraulic simulations. The overall outcome of the simulations indicates a possible solution on how to cement back to the previous Casing shoe
Federico Nietze - One of the best experts on this subject based on the ideXlab platform.
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chemicals systems used in the exploitation at the miravalles geothermal field costa rica calcium carbonate inhibition systems for neutral wells and neutralization systems for acid wells
2015Co-Authors: Federico NietzeAbstract:The reservoir fluids are over-saturated with respect to calcium carbonate at the flashing zone in most of the Miravalles Geothermal Field. Without a calcium carbonate inhibition system, the mineral is deposited on the Production Casing of the well, losing flow (and energy), in few time .The implementation of the inhibition system has been successfully applied since 1994, therefore Production problems by obstruction and mechanical cleanouts are minimized by optimizing the process (like an appropriate dose). On the other hand, optimization of the products used has been managed, both in quality and price. Furthermore, about five wells have acidic fluids with a pH value between 2.3 to 3.2. Furthermore, about five wells have acidic fluids with a pH value between 2.3 to 3.2. However, two of them are in Production today (PGM-07 since 2001 and PGM-02 since 2006) by the neutralization system implementation, which has been used successfully, allowing the use of the resource to generate 10 MW in plants. There are twenty two systems for inhibition of calcium carbonate scale and three neutralization systems (two of them on line). Some economic aspects are discussed under the appropriate sections.
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benefits from the utilization of a calcium carbonate inhibition system for Production wells at the miravalles geothermal field
2005Co-Authors: Paul Moya, Federico Nietze, Antonio YockAbstract:The Miravalles Geothermal Field has been producing electric energy since March 1994. It has provided steam for Unit 1 (55 MWe) since 1994, a Wellhead Unit (5 MWe) installed in 1995, Unit 2 (55 MWe) in 1998, Unit 3 (29 MWe) in 2000, and Unit 5 (19 MWe, a binary plant) in the year 2004. During the first Production tests of wells in the field, it was found that the reservoir fluids are oversaturated with respect to calcium carbonate at the flashing zone, causing deposition of this mineral and obstruction of the Production Casing within few days. A test conducted in 1989 proved that systematic chemical inhibition inside the Production wells could prevent the formation of calcite scale. All the inhibitors tested in the field are described in this article. Since 1994, the inhibition system has been used successfully in the Production wells that supply steam to the generating Units. Experience has indicated that the injection of an appropriate dose of inhibitor makes it possible to produce the geothermal wells with little or no deposition of calcium carbonate, and it is less expensive than performing mechanical cleanouts.
Yu Song - One of the best experts on this subject based on the ideXlab platform.
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mechanism of pressure management by injecting nitrogen in Casing annulus of deepwater wells
Petroleum Exploration and Development, 2015Co-Authors: Bo Zhou, Xiaolong Huang, Rongxin Zhou, Yu SongAbstract:Abstract The influence factors of annular pressure buildup are analyzed, and the temperature and pressure characteristics of annulus trap medium are simulated for deepwater wells. The method of pressure management by injecting nitrogen in Casing annulus is proposed based the experiment result. Limited by the well structure and subsea system, long Casing annulus exists between technical Casing and Production Casing and it is filled with water-based, synthetic based or oil-based drilling fluid. In the process of oil/gas test and Production, the temperature of the trapped fluid rises significantly under the influence of the well-bore fluid and the trap pressure buildup appears because of liquid heat expansion. Experiments show that isothermal compressibility coefficient and thermal expansion coefficient are the key influencing factors for annulus pressure buildup. Trap pressure is very sensitive to the type of trapped medium (liquid, gas). Injecting 5%−20% volume fraction of nitrogen into the annulus can effectively control the annulus pressure build-up, and avoid Casing collapse. Field practice shows that the method, convenient and highly reliable, can ensure the borehole safety during testing and Production of deepwater oil and gas.
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Mechanism of pressure management by injecting nitrogen in Casing annulus of deepwater wells
KeAi Communications Co. Ltd., 2015Co-Authors: Bo Zhou, Jin Yang, Xiaolong Huang, Rongxin Zhou, Zhengli Liu, Junfeng Luo, Yu SongAbstract:The influence factors of annular pressure buildup are analyzed, and the temperature and pressure characteristics of annulus trap medium are simulated for deepwater wells. The method of pressure management by injecting nitrogen in Casing annulus is proposed based the experiment result. Limited by the well structure and subsea system, long Casing annulus exists between technical Casing and Production Casing and it is filled with water-based, synthetic based or oil-based drilling fluid. In the process of oil/gas test and Production, the temperature of the trapped fluid rises significantly under the influence of the well-bore fluid and the trap pressure buildup appears because of liquid heat expansion. Experiments show that isothermal compressibility coefficient and thermal expansion coefficient are the key influencing factors for annulus pressure buildup. Trap pressure is very sensitive to the type of trapped medium (liquid, gas). Injecting 5%−20% volume fraction of nitrogen into the annulus can effectively control the annulus pressure build-up, and avoid Casing collapse. Field practice shows that the method, convenient and highly reliable, can ensure the borehole safety during testing and Production of deepwater oil and gas. Key words: deepwater well, annular pressure buildup, annular temperature, nitrogen foam, pressure managemen
Fei Yin - One of the best experts on this subject based on the ideXlab platform.
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prediction of sustained Production Casing pressure and Casing design for shale gas horizontal wells
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Fei Yin, Deli GaoAbstract:Abstract Casing failure in shale gas horizontal wells hinders the efficient development of shale gas. The sustained Casing pressure is the main failure mechanism, while the current analytic methods are not fit to shale gas horizontal wells. Hydraulic fracturing causes well temperature change, so the temperature distribution of horizontal well section is calculated based on heat transfer theory. According to thermoelasticity, the formula of annular volume change under the synergy of temperature and pressure is deduced. By substituting the temperature distribution and annular volume change into the prediction model, the sustained Production Casing pressure in horizontal wells is obtained. For the work condition of Production Casings in shale gas horizontal wells, an improved method of Casing design is proposed. Results indicate that the horizontal well temperature increases with the distance increase from well axis in the pattern of line-parabola. The thermoelastic deformations of Production Casing and surrounding rock change the annular volume observably. The sustained Production Casing pressure displays a quadratic polynomial increase with well temperature. The hydraulic fracturing pressure and sustained Casing pressure should be involved to design the Production Casing in shale gas horizontal wells. The research provides the prediction method of sustained Production Casing pressure in horizontal wells. The proposed Casing design method for shale gas horizontal wells ensures well integrity.
