A Chemical Method of Achieving Uniform Stimulation Intensity Along Long Laterals in Horizontal Wells
Bibliographic record
Abstract
Abstract To exploit a reservoir more efficiently, horizontal wells with long laterals are being drilled in many oilfields in the world. Uniform acidizing by bullheading is a challenge in these wells because the volume of acid that enters each segment tends to be different: larger at the heel while smaller at the toe. This further causes a non-uniform production profile which advances breakthrough of water. In this paper, a method of using a temperature-sensitive viscous acid to achieve uniform stimulation profile is introduced. The acid is delicately designed so that the viscosity of it changes with temperature and the changing rate can be quantitatively controlled. As the acid flows in wellbore, the diffusion coefficient of H+ and therefore the acid-rock reaction rate gradually increases while it is being warmed by wellbore. A model describing the change of viscosity and H+ mass transfer coefficient is established and coupled with a wellbore heat transfer model. The basic of this acid is hydrochloric acid but it is mixed with a special gelatinizer. The initial viscosity of the acid ranges from 60 to 1400 mPa.s at surface, depending on the concentration of gelatinizer. Its viscosity gradually decreases to 200 mPa.s with temperature increasing to 100 ℃.The leaking off velocity decreases from 2.0×10−6 m/s to 2.0×10−7 m/s accordingly, depending on the injecting time. And the acid concentration at the wall of wellbore increase by three times when the injecting rate doubles, also depending on the wellbore temperature and pressure. The acid-rock reaction rate is faster at toe than at heel, which just compensates the differences of acid volume allocation between toe and heel due to wellbore flow friction. A model describing the correlations between the acid viscosity, diffusion coefficient of H+, the concentrations of HCl, the injection rate and the temperature is generated. This model is coupled with an acid flow and reaction model and a wellbore heat transfer model and in the end a profile of H+ consumption along the lateral is predicted. With use of this model, by adjustment of acid formula and injection rate, a uniform stimulation intensity profile along the long lateral can be achieved. A well case is introduced to show the application of this model. The dynamic temperature profile, the acid viscosity profile, the allocation of hydrogen ions as well as the equivalent wormhole lengths along the wellbore are all given in the paper. This paper introduces a chemical way to achieve uniform acidizing intensity in horizontal wells with long laterals without running in mechanical tools, reducing cost and leaving a good wellbore environment for future well interventions after treatment.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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) | 0.001 | 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".