A Tubing Anchor Engineered for Rod Pumping Horizontal Wells Improves Production Performance
Bibliographic record
Abstract
High gas to oil ratio (GOR) producing horizontal wells is now commonplace. This ratio continues to rapidly escalate as reservoirs suffer regional and basin wide pressure depletion. The North Dakota Bakkeni formation is a prime example of a concerning GOR trend and can be seen in Figure 1. Higher GOR's and depleted reservoir pressures lead to increased gas rates and multiphase fluid velocities within horizontal wellbores. Increased multiphase fluid velocities can then transport more damaging solids to a sucker rod pump and increase failure frequencies. Consequently, challenges for controlling failure frequencies and workover costs with sucker rod pumping continues to intensify, especially for improving downhole gas and solids separation. Sucker rod pumping normally requires the tubing string to be secured or anchored to the casing, downhole near the sucker rod pump. Anchoring of tubing prevents tubing movement during a rod pump's operating cycle. Tubing movement can undesirably reduce downhole pumping efficiency and increase risks for damage to the tubing, casing, pump and sucker rods. A downhole tubing anchor (TA) or a downhole tubing anchor catcher (TAC) are a bottomhole assembly component installed for this purpose, but they can present risks for increasing operating expenses and limiting of a well's production potential. Production can be limited if the annular flow path cross-sectional area of a tubing anchor (to the casing's internal diameter) is a flow path restriction. A flow path restriction negatively impacts downhole gas separation performance by causing multiphase flow instabilities. Further, sluggy and inconsistent multiphase flows that commonly emanate from a horizontal wellbore can worsen from a flow restriction, making downhole gas separation even more challenging. Flow restrictions can increase turbulence and then cause undesirable foaming and gas entrainment. Foaming of fluids is generally characterized by smaller gas bubbles in the liquid, which are more difficult to separate from the liquid.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".