Producer Acid Stimulation in Unconsolidated Sandstone Reservoirs: Continuous Evolution in Overcoming Challenges and Enhancing Well Performance in an Offshore Oil Field
Bibliographic record
Abstract
Abstract The objective of this paper is to review the evolution of producer acid design and the well performance of different acid formulations in an offshore oilfield in China. The focus is on addressing the persistent near wellbore plugging challenges encountered after water breakthrough. Over the past 15 years, acid stimulation in studied oil field has experienced five major modifications since 2007. Initially, acid design considered potential causes of plugging only. However, after evaluating well performance and identifying new challenges arising from acid stimulation, an optimized process was developed. This process includes plugging mechanism analysis, experimental acid formulation selection, acid deployment, and comprehensive performance evaluation. Evaluation parameters encompass changes in productivity index (PI), oil and liquid production, skin, flow efficiency, and the impact on production facilities. Simplifying the operational process to reduce operational cost (Opex) has been a consistent goal and a key consideration in acid design assessment. Continuous optimization in acid stimulation has been achieved through years of experience and lessons learned. The acid system has progressed from hydrochloric acid (HCl) system to a slow-released hydrofluoric (HF) based acid system, and later to a moderate-strength HF based acid system, and later to a weaker chelant acid system. The novel chelant acid system has been introduced as an alternative to moderate-strength HF based acid system, offering low corrosion, low reaction rate, and high efficiency, making it particularly effective for stimulating plugged producers in waterflooded unconsolidated sandstone reservoirs. Initially, this acid system demonstrated moderate production incremental; however, through continuous acid formulation and process optimization, its current results are comparable to those of the moderate-strength HF based acid system. The operation process has become simpler, minimizing its impact on the production facility through ongoing optimization. This paper also introduced the recent advancements in the emulsified acid system, which has improved acid distribution across intervals exceeding 500 feet in thickness. Implemented in 2021, this advancement has shown promising production outcomes. This paper will primarily focus on the evolution of the chelant acid system and the latest application of the emulsified acid system. It will discuss the continuous optimization of acid systems and operational processes, and will also cover field well selection criteria, well performance, and the impact of these processes on production facilities.
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 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 | 0.001 | 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".