Transient Fluid and Heat Flow Modeling in Coupled Wellbore/Reservoir
Systems

Izgec, Bulent; Kabir, Shah; ding, zhu; Hasan, A.

doi:10.2523/102070-ms

Cited by 13 publications

(11 citation statements)

References 7 publications

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“…The temperature distribution in the wellbore can be derived on the basis of the fluid-energy balance and heat transfer equations. It is assumed that [29,30] (1) the heat transfer in the wellbore is in a steady state, while the heat transfer from wellbore to the formation is in a non-steady state; (2) only radial heat transfer is considered; and (3) the formation temperature varies proportionally with depth. Therefore, the equilibrium equation for the element dH, which is shown in Figure 3, can be expressed as…”

Section: Temperature Distribution In Annulusmentioning

confidence: 99%

Acoustic Wave-Based Method of Locating Tubing Leakage for Offshore Gas Wells

Liu

Fan

2018

Energies

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This paper presents a novel acoustic wave-based method for the detection of leakage in downhole tubing of offshore gas wells. The localization model is developed on the basis of analyzing the propagation model of leakage acoustic waves and the critical factors in localization. The proposed method is validated using experimental laboratory investigations that are conducted to locate tubing leakage by setting five holes at different positions on the tubing wall. A detection system is developed for the leakage acoustic waves in the tubing-casing annulus, where one acoustic sensor is installed at the annulus top. Laboratory experimental results show that the depth of downhole leakage can be effectively located by using the proposed localization model. The localization errors are kept at a very low level, and are mainly generated from extracting the characteristic time and calculating annular acoustic velocity. A case study focusing on an offshore gas well is presented to illustrate the feasibility of the proposed method, and to demonstrate that the proposed model can locate the liquid level and leakage points under field conditions. The test can be performed without interrupting the production of gas wells.Energies 2018, 11, 3454 2 of 21 by each sensor. The instrument does not move in the tubing. The test precision is relatively improved by the distributed sensor array. However, the results greatly rely on the reliability of the instrument and the efficiency of signal processing. The current implementation of logging and distributed sensor arrays requires the instrument to be placed in the tubing, and the well needs to be shut down during testing. This process usually entails large costs and risk. Therefore, detecting tubing leakage without interrupting well production is necessary.Tubing leakage will cause pressure changes in the tubing-casing annulus. Zhu et al. have introduced a calculation model of tubing leak depth based on the pressure balance principle when investigating the prediction model of annulus pressure in the CO 2 injection well [11]. Wu et al. further studied this principle and extended it to production gas wells [12,13]. The Bayesian inference is introduced to handle the uncertainties in leakage location forecasting that are caused by variations in reservoir conditions and measurement errors. Meanwhile, an annulus pressure monitoring system is developed to assist diagnosis. This method is theoretically feasible, and does not affect the well production. However, the accuracy of results greatly relies on the wellbore fluid calculation and production status. The locating process needs the production and annulus pressure to be kept stable. This method also requires accurate liquid level information in the annulus, and is not suitable for a well that leaks at an excessive inclination or horizontal sections. Zhang et al. presented a method based on the application of a He tracer [14]. The tracers are injected from the annulus and detected at the choke. The leak depth is calculated by using the flowing tim...

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Section: Temperature Distribution In Annulusmentioning

confidence: 99%

Acoustic Wave-Based Method of Locating Tubing Leakage for Offshore Gas Wells

Liu

Fan

2018

Energies

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“…Kabir et al (1996) presented wellbore/reservoir simulator for gas single phase flow, and it was extended to oil single phase flow (Hasan et al, 1997) and two-phase flow (Hasan et al, 1998). Izgec et al (2007) used a semi-analytical heat transfer model by replacing the finite-differential energy equation used in Kabir et al model for efficient computation. In these models, the analytical formation temperature model presented by Hasan and Kabir (1991) was used, and the temperature of the reservoir inflow was assumed to be the same with the formation temperature.…”

Section: Temperature Modeling and Interpretationmentioning

confidence: 99%

Temperature Prediction Model for a Horizontal Well with Multiple Fractures in a Shale Reservoir

Yoshida

2013

SPE Annual Technical Conference and Exhibition

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Downhole temperature measurements either by permanent sensors or temporarily conveyed tools provide information that has been used in many production diagnosis applications. This paper presents a study that correlates the temperature behavior to the flow profile in a multi-stage fractured horizontal well. The ultimate goal is to interpret well performance and to optimize fracture treatment design from monitored temperature data. This study has developed flow and thermal models for horizontal wells with transverse fractures. The system was divided into a horizontal wellbore and a reservoir having multiple fractures in the study. The wellbore flow and thermal model were formulated based on mass, momentum and energy balance. Numerical reservoir simulation was adopted for the reservoir flow problem, and the reservoir thermal model was formulated by a transient energy balance equation considering viscous dissipation heating and temperature variation caused by fluid expansion besides heat conduction and convection. In the reservoir system, the primary hydraulic fractures perpendicular to the horizontal well were modeled with thin grid cells explicitly, and the fracture network around the horizontal well was modeled as an enhanced permeable zone with respect to the unstimulated matrix permeability. The reservoir grids between two fractures were logarithmically spaced to capture transient flow behavior. The reservoir flow and thermal model was coupled with the wellbore model to predict the temperature distribution in a horizontal wellbore. The results of the model show two main mechanisms in this thermal problem: heat conduction by formation heating/cooling effects at non-perforated zones, and wellbore fluid mixing effects with reservoir inflow at fracture locations (fluid entry points). The examples in the paper illustrated that the models can be used to predict temperature profiles in stimulated horizontal wells for identical or non-identical transverse fractures. Sensitivity studies were performed to evaluate the influences of fracture conductivity and half-length on temperature behavior in the defined system. The results indicate that the wellbore temperature is primarily sensitive to fracture geometry (fracture half-length). It is possible to interpret the fracture geometry using temperature data after the flow rate is stabilized after certain period of production. In addition, wellbore temperature is also sensitive to fracture conductivity. However, the signal of high fracture conductivity diminishes, and after the surface flow is stabilized, the signal might not be identified by temperature measurement. Real time temperature data measurement is helpful for the evaluation of fracture conductivity.

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“…The model was then employed to evaluate thermal breakthrough in the geothermal doublet system [7] and to describe horizontal conduction and convection in the reservoir and vertical conduction in the confining rock (caprock and bedrock) [8][9][10]. Nonisothermal heat exchange between fluid in the fractures and matrix [11] and coupled heat-fluid transport processes in both wellbore and reservoirs were considered as well [12][13][14]. The analytical solutions offered fast and sound tools to understand the principles of HT processes in the subsurface.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Energy Production in the Deep Carbonate Geothermal Reservoir by Wellbore-Reservoir Integrated Fluid and Heat Transport Modeling

et al. 2019

Geofluids

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Geothermal energy is clean and independent to the weather and seasonal changes. In China, the huge demanding of clean energy requires the geothermal energy exploitation in the reservoir with depth larger than 1000 m. Before the exploitation, it is necessary to estimate the potential geothermal energy production from deep reservoirs by numerical modeling, which provides an efficient tool for testing alternative scenarios of exploitation. We here numerically assess the energy production in a liquid-dominated middle-temperature geothermal reservoir in the city of Tianjin, China, where the heat and fluid transport in the heterogeneous reservoir and deep wellbores are calculated. It is concluded that the optimal injection/production rate of the typical geothermal doublet well system is 450 m3/h, with the distance between geothermal doublet wells of 850 m. The outflow temperature and heat extraction rate can reach 112°C and 43.5 MW, respectively. Through decreasing injection/production rate lower than 450 m3/h and optimizing layout of the injection well and production well (avoiding the high permeability zone at the interwell sector), the risk of heat breakthrough can be reduced. If the low permeability zone in the reservoir is around injection well, it usually leads to abnormal high wellhead pressure, which may be solved by stimulation technique to realize stable operation. The methodology employed in this paper can be a reference for a double-well exploitation project with similar conditions.

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Transient Fluid and Heat Flow Modeling in Coupled Wellbore/Reservoir Systems

Cited by 13 publications

References 7 publications

Acoustic Wave-Based Method of Locating Tubing Leakage for Offshore Gas Wells

Acoustic Wave-Based Method of Locating Tubing Leakage for Offshore Gas Wells

Temperature Prediction Model for a Horizontal Well with Multiple Fractures in a Shale Reservoir

Assessment of Energy Production in the Deep Carbonate Geothermal Reservoir by Wellbore-Reservoir Integrated Fluid and Heat Transport Modeling

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