An Integrated Sand Cleanout System by Employing Jet Pumps
Bibliographic record
Abstract
Abstract Sand cleanout is operated by circulating a liquid or a multi-phase fluid into the wellbore to bring the sand particles to the surface. Although the sand cleanout operations have been applied successfully in most wells with high efficiency and negligible leakage, failure of effective sand removal always occurs in low pressure wells and absorption wells due to heavy loss of circulation. To make the matter worse, solids in the bottomhole may even flow back into the formation to cause further formation damage around the wellbore. In this paper, an integrated sand cleanout system has been developed to effectively remove loose sand particles in low pressure wells and absorption wells by employing a jet pump. More specifically, a high-pressure working fluid is pumped through the annulus from the surface and then divided into two parts. One part of the fluid is diverted as the sand carrier fluid to flow downwards, stir up the sand particles via a jetting nozzle at the bottom of a sand cleanout pipe, bring the loose sand particles upwards and then to be boosted by using a jet pump. The other part of the fluid acts as the power fluid of the jet pump to reduce the bottomhole pressure so that the carrier fluid together with the sand particles will be sucked into the pump and then lifted to the surface. Detailed structure and principle of the integrated sand cleanout system are described, while a theoretical model is formulated to optimally design the system based on the experiment data and jet pumping theory. It has been shown from field applications that the integrated sand cleanout system makes significant improvement in achieving high efficiency and preventing leakage in low pressure wells and absorption wells. Introduction Increasing interests and efforts have been focused on sand cleanout in the upstream oil and gas industry since 1960s[1]. Although 60% of the oil and gas reserves are discovered in carbonate reservoirs, approximately 90% of the world's oil and gas wells are drilled in sandstone reservoirs, among which 25 to 35% of the wells experience certain degree of sand production during the life of the well[2]. In principle, sand particles are dragged by the formation fluids, carried out from the formation and settled down at the bottom of the well. By the time the casing is full of the sedimentary solids, the pay zone becomes plugged and the downhole pump gets stuck, workover activities have to be carried out for reviving the well back into production[3]. Frequently, wellbore fill removal is considered inadequate, leaving large quantities of fill material (e.g., sand particles) in the well, which often requires repeating well cleanouts in a relatively short time interval. In addition, wellbore cleanouts are extremely time-consuming, preventing timely return of wells to production and increasing the cost of well maintenance[4].
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".