The Use of Lightweight Cement Slurries and Downhole Chokes on Air-Drilled Wells
Bibliographic record
Abstract
Summary The success of a primary cement job is often measured according to effective zonal isolation, achieving the designed top of cement, and avoidance of remedial cementing. In the San Juan and Rio Arriba counties of New Mexico, many Mesa Verde and Dakota wells are air-drilled because the Mesa Verde formation is subnormally pressured and naturally fractured. This combination makes the Mesa Verde easy to hydraulically fracture during normal drilling and cementing operations. Therefore, meeting the primary-cement-job success criteria is particularly challenging. Cementing of casing within an air-drilled wellbore allows the slurry to free fall. Cement free fall can cause severe surge pressures at the bottom of the hole, leading to hydraulic fracture initiation and loss of lift. Theuse of a downhole choke (DHC) can be employed to prevent these processes from occurring. Because mud filter cake does not exist in an air-drilled hole, the lead water spacer and cement must wet the casing and wellbore rock surfaces. Loss of the lead water spacer, in conjunction with cement water loss, can produce dehydration of the cement column, leading to an increase incement viscosity and equivalent circulating density. Careful control of cement-free water and fluid loss are required to prevent this from occurring. Further more, placing cement across targeted completion intervals that have low fracture gradients requires the use of ahigh-compressive-strength, low-density cement that is competent and capable of maintaining zonal isolation during the completion and production phases of well construction. This paper will outline the evolution of the cementing practices used forthe Mesa Verde and Dakota wells drilled in the 29-6 Unit (T29N−R6W, New Mexico) from 1998 to 2002. It will illustrate how cementing changes enabled the primary cementing to be successfully completed in a single stage instead of two, which has translated into cost savings for both the drilling and completion phases of a well. The impact of using a DHC for the pumping and placement of these primary cement jobs will be illustrated and discussed. The function of the cement additives on slurry properties will also be discussed as they pertain to these cement jobs.
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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".