Interpretation and Analysis of Transient Sandface and Wellbore Temperature Data

Summary This paper presents new analytical and semianalytical solutions derived from a coupled transient-wellbore/reservoir thermal model to investigate the information content of transient-temperature measurement made within the vertical wellbore across from the producing horizon or at a gauge depth above it during drawdown and buildup tests. The solutions consider flow of a slightly compressible, single-phase fluid in a homogeneous infinite-acting reservoir system with skin modeled as a composite zone adjacent to the wellbore and account for the Joule-Thomson (J-T) heating/cooling, adiabatic-fluid expansion, conduction and convection effects both in the wellbore and reservoir. They are developed depending on the assumption that the effects of temperature changes on wellbore and reservoir-pressure-transient data can be neglected so that the mass-, momentum-, and energy-balance equations in the wellbore and reservoir can be decoupled. The semianalytical solution for predicting sandface temperatures is verified by use of a general-purpose thermal simulator. Wellbore temperatures at a certain gauge depth are evaluated through the analytical steady-state and transient-wellbore-temperature equations coupled with a semianalytical reservoir-temperature model accounting for conservation of momentum in the wellbore. Results show that drawdown- and buildup-sandface-temperature data may exhibit two semilog straight lines: one at early times reflecting the effects of adiabatic-fluid expansion in the skin zone near the wellbore, and the other, the late-time semilog straight line, reflecting the J-T effects and exhibiting the nonskin-zone properties. However, the wellbore-temperature measurements made at locations above the producing horizon may not exhibit these semilog straight lines because they are strongly dependent upon distance above the producing horizon, geothermal gradient, and radial-heat losses from the wellbore fluid to the formation on the way to gauge. It is found that the skin-zone properties are very difficult to be estimated from drawdown- and buildup-wellbore temperatures unless the gauge location is not far from the producing zone. Specifically, we found that buildup-wellbore temperature is mostly dominated by wellbore-heat losses compared with drawdown-wellbore-temperature data, and hence may not be useful to estimate the formation properties, including skin-zone properties.

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Prospects for Assessing Enhanced Geothermal System (EGS) Basement Rock Flow Stimulation by Wellbore Temperature Data

Energies ◽

10.3390/en10121979 ◽

2017 ◽

Vol 10 (12) ◽

pp. 1979 ◽

Cited By ~ 3

Author(s):

Peter Leary ◽

Peter Malin ◽

Tero Saarno ◽

Ilmo Kukkonen

Keyword(s):

Temperature Data ◽

Geothermal System ◽

Enhanced Geothermal System ◽

Basement Rock ◽

Wellbore Temperature ◽

Flow Stimulation

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Permeability, Skin, and Inflow-Profile Estimation From Production-Logging-Tool Temperature Traces

SPE Journal ◽

10.2118/174910-pa ◽

2017 ◽

Vol 22 (04) ◽

pp. 1123-1133 ◽

Cited By ~ 6

Author(s):

Jeff App

Keyword(s):

History Matching ◽

Synthetic Data ◽

Relative Effect ◽

Temperature Data ◽

Transient Model ◽

Pressure Profiles ◽

Single Temperature ◽

Wellbore Temperature ◽

Inflow Profile ◽

Logging Tool

Summary Temperature traces from multiple rates are used to estimate the production-inflow profile and layer permeability and skin by use of a transient coupled reservoir/wellbore model. Production-logging-tool (PLT) temperature traces from two rates show heating of approximately 6–11°F above the geothermal because of the Joule-Thomson expansion of the reservoir oil. Production is single-phase oil from a high-pressure oil reservoir. Nonlinear regression was used to automatically adjust the layer permeability and skin values until the observation temperature traces from both rates were matched. History matching the temperature data provides a quantitative estimate of the skin and permeability within each contributing layer; this cannot be obtained from conventional pressure-transient analysis, which, unless for highly specialized cases, provides only a single value of permeability and skin. The production-inflow profile is then constructed by use of the history-matched layer permeability and skin values. In addition to the wellbore-temperature profiles, temperature and pressure profiles within the reservoir will be shown that illustrate the relative effect of the reservoir permeability and skin on the wellbore-temperature responses. The approach in this paper is different from many of the previous studies in the literature, in which only a single temperature trace is history matched and often under the assumption of steady-state conditions. Furthermore, no studies were found in which multiple temperature traces were matched by use of a transient model in which the temperature data were field data as opposed to synthetic data. Information on the coupled reservoir/wellbore model and the optimizer will be provided.

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