Wellbore Thermal Performance and Its Impact on Flow Assurance Design of a Subsea Production System
Bibliographic record
Abstract
Abstract In many flow assurance designs for subsea production systems, a single assumed rock-layer thickness surrounding the subsea wellbore is used to simulate wellbore thermal performance over the well's entire projection life. This assumption may lead to significant errors in flowing wellhead temperature calculations and potential failure of the flow assurance thermal design. Based on the Ramey wellbore heat transfer model, this paper presents a new generalized equivalent rock-layer thickness (ERT) model with a time-dependent impact zone of the formation rock-layer surrounding the wellbore. The equivalent thickness of the impact zone of the formation depends on the production time for a producer (or the injection time for an injector). It can be determined by the Ramey dimensionless time function. Various drill-stem-test (DST) data, field production data, and OLGA simulation results have verified the validity of the proposed model. The ERT model can be used to determine the wellbore U-value (overall heat transfer coefficient) and thermal performance during early, mid, and late life for flow assurance design. Introduction In the early 1960s, Ramey1 published a classic paper on wellbore heat transmission to present a simple analytical equation for wellbore temperatures based on a simplified heat balance for single-phase liquid or gas flow. Ramey also proposed a procedure to estimate the wellbore U-value for heat losses, comprising both the near-wellbore heat resistance and the transient heat resistance in the formation rock, in terms of a dimensionless time function. Since then numerous efforts have been made to solve the wellbore heat transfer equations related to single-phase flow or multi-phase flow in the wellbore. In 2004, Hagoort2 revisited Ramey's classic method and presented the rigorous solution to the wellbore heat balance equations. Hagoort demonstrated that Ramey's method is an excellent approximation for the calculation of temperatures in injection and production wells (except for an early transient period) and that the estimation of the overall heat transfer coefficient (related to the dimensionless time function) is good for long production or injection times. Wellbore thermal performance is a key factor to be considered in the flow assurance design of subsea production systems. Using commercial simulators such as OLGA, the equivalent thickness of the formation rock-layer surrounding the wellbore has to be assumed to calculate the U-value of the wellbore in steady state and transient simulations. This assumption may lead to significant errors in flowing wellhead temperature for normal operation, cooldown time for shutdown, and warm-up time for restart if a single rock-layer thickness is used over the entire field life. To avoid these errors and potential failure of the flow assurance thermal design, this paper presents a simple general equivalent rock-layer thickness (ERT) model that can be applied for flow assurance design work.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".