Numerical and analytical modelling of sandface temperature in a dry gas producing well (original) (raw)
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Transient Fluid and Heat Flow Modeling in Coupled Wellbore/Reservoir Systems
All Days, 2006
This paper presents a transient wellbore simulator coupled with a semianalytic temperature model for computing wellbore-fluid-temperature profile in flowing and shut-in wells. Either an analytic or a numeric reservoir model can be combined with the transient wellbore model for rapid computations of pressure, temperature, and velocity. We verified the model with transient data from multiple gas and oil wells, where both surface and downhole data were available. The accuracy of the heat-transfer calculations improved with a variable-earth-temperature model and a newly developed numerical-differentiation scheme. This approach improved the calculated wellbore fluid-temperature profile, which, in turn, increased the accuracy of pressure calculations, at both bottomhole and wellhead. The proposed model accurately mimics afterflow during surface shut-in by computing velocity profile at each timestep and its consequent impact on temperature and density profiles in the wellbore. Surrounding ...
Energies
Accurate characterization of heat transfer in a wellbore during drilling, which includes fluid circulation, is important for wellbore stability analysis. In this work, a pseudo-3D model is developed to simultaneously calculate the heat exchange between the flowing fluid and the surrounding media (drill pipe and rock formation) and the in-plane thermoelastic stresses. The cold drilling fluid descends through the drill pipe at constant injection rates and returns to the ground surface via the annulus. The fluid circulation will decrease the wellbore bottom temperature and reduce the near-wellbore high compressive stress, potentially leading to tensile fracturing of the well. The governing equations for the coupled heat transfer stress problem are formulated to ensure that the most important parameters are taken into account. The wellbore is subject to a non-hydrostatic in situ far-field stress field. In modeling heat exchange between fluid and surrounding media, the heat transfer coefficients are dependent on fluid properties and flow behavior. Analytical solutions in the Laplace space are obtained for the temperatures of the fluid in both the drill pipe and annulus and for the temperature and stress changes in the formation. The numerical results in the time domain are obtained by using an efficient inversion approach. In particular, the near-well stresses are compared for the cases with fixed and time-dependent cooling wellbore conditions. This comparison indicates that the using a fixed temperature wellbore conditions may overestimate or underestimate the bottom-hole stress change, potentially leading to wellbore stability problems.
Temperature Transient Tests: Modeling, Interpretation, and Nonlinear Parameter Estimation
2019
This study presents semi-analytical and analytical solutions based on a coupled transient wellbore/reservoir thermal model to predict temperature transient measurements made under constant rate and bottom-hole pressure production as well as variable rate and bottom-hole pressure production histories in a vertical or an inclined wellbore across from the producing horizon or at a gauge depth above it. Slightly compressible, single-phase, and homogeneous infinite-acting single-layer geothermal reservoir system is considered. The models account for Joule-Thomson heating/cooling, adiabatic fluid expansion, conduction and convection effects both in the reservoir and wellbore. The transient wellbore model accounts for friction and gravity effects. The solutions of the analytical and semi-analytical reservoir models are verified by use of a general-purpose thermal simulator. Wellbore temperatures at a certain gauge depth are evaluated through a wellbore thermal energy equation coupling the ...
Estimation of heat-flow rate: A precursor to the transient-temperature analysis
Geothermics, 2020
Fluids in a reservoir remain in equilibrium condition before the onset of any wellbore operation. This equilibrium pertains to both the fluid pressure and temperature. Inducing any wellbore activity, such as mud circulation in drilling and fluid production precipitate changes in both the pressure and temperature responses. For an infinite-acting system, we can solve the governing temperature diffusivity equation by adopting the line-source solution. The difference between the pressure and temperature diffusivity equation allows us to investigate an independent line-source solution for the temperature-diffusivity equation. After obtaining the temperature linesource solution, we determined the temperature behavior for different wellbore temperature measurements during the shut-in period, such as those reflecting buildup and falloff responses. This study presents a mathematical approach to study the temperature falloff measurements and another method for the buildup temperature dataset. In particular, we used the estimated heat-flow rate to convolve with temperature for improving the quality of initial-formation temperature estimation. Finally, the heat flow corresponding to each timestep and the application of superposition principle was also investigated. The temperature line-source solution represented the backbone for all suggested approaches.
Geofluids, 2018
Well test analysis requires a preselected model, which relies on the context input and the diagnostic result through the pressure logarithmic derivative curve. Transient pressure outer boundary response heavily impacts on the selection of such a model. Traditional boundary-type curves used for such diagnostic purpose are only suitable for single-phase flow in a homogeneous reservoir, while practical situations are often much more complicated. This is particularly true when transient pressure is derived during the field development phase, for example, from permanent down-hole gauge (PDG), where outer boundary condition such as an active aquifer with a transition zone above it plays a big role in dominating the late time pressure response. In this case, capillary pressure and the total mobility in the transition zone have significant effect on the pressure response. This effect is distinctly different for oil-water system and gas water system, which will result in the pressure logarit...
Pressure-transient analysis in shale gas reservoirs: A review
Journal of Natural Gas Science and Engineering, 2020
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Computing flow profiles and total flow rate with temperature surveys in gas wells
Journal of Natural Gas Science and Engineering, 2012
Distributed temperature sensing or DTS is gaining increasing popularity because of its potential to generate flow profiles over completed intervals. In fact, several studies have reported successful reproduction of field data, obtained with conventional production logs, in both vertical and deviated wells. One input that enters into typical DTS calculations is the total flow rate at surface. In absence of dedicated flowmetering, uncertainty normally creeps into assigned well rates. This study provides a methodology wherein both the total and individual layer rates can be computed independently with DTS, completion, tubular, and other related data. To do the entire suite of calculations, a wellbore model handling steady fluid flow and unsteady-state heat transfer estimates a production rate, given wellhead pressure and temperature. The same model is then used to compute the flow profile based on measured DTS data across the producing intervals. The model rigorously accounts for various thermal properties of the fluid and the formation, including JouleeThompson (JT) heating or cooling. Examples from both gas and oil wells are shown to illustrate the application of the proposed methodology. Good correspondence between the measured and calculated results demonstrates the robustness of the proposed method.
Transient pressure analysis of gas wells producing at constant pressure
Journal of Petroleum Science and Engineering, 2003
A comprehensive investigation of the validity of applying the constant-pressure liquid solution to transient rate-decline analysis of gas wells is presented. Pseudo-pressure, non-Darcy flow effects, and formation damage are incorporated in the liquid solution theory to simulate actual real gas flow around the wellbore. The investigation shows that for constant-pressure gas production, the conventional semilog plot of the inverse of the dimensionless rate versus the dimensionless time used for liquid solution must be modified to account for high-velocity flow effects. Especially when reservoir permeability is higher than 1 md and the well test is affected by non-Darcy flow and formation damage.
2020
Resumo -.A estimativa do campo de temperatura em torno do poço é um importante problema na engenharia de petróleo. O calor é transferido entre o poço e a formação durante os processos de recuperação térmica, induzindo tensões que podem afetar a estabilidade estrutural do poço e da formação. O campo de temperatura em torno do poço tem sido avaliado por técnicas numéricas como o método das diferenças finitas ou inversão numérica da transformada de Laplace, supondo uma temperatura constante na parede do poço. O método aqui proposto considera a condução radial do calor através da parede do poço, sendo este composto por múltiplas camadas cilíndricas de materiais distintos com propriedades físicas constantes e em perfeito contato térmico. A solução para a equação de condução utiliza o método da separação de variáveis, através das funções de Bessel. O domínio do problema é definido num intervalo finito limitado pelo raio de influência, avaliado conforme o avanço da frente de calor. A condi...