A New Methodology to Forecast Solution Gas Production in Tight Oil Reservoirs
Bibliographic record
Abstract
Abstract Due to favorable economics, more and more oil companies are now drilling multi-stage fractured horizontal wells to develop tight oil reservoirs. While oil production forecasting in these wells has historically been the primary focus of most operators, gas (solution gas) production forecasting has been largely neglected. There are two distinct reasons for this oversight: First, when compared to oil production, solution gas rates typically have a much lower impact on overall economics. Second, solution gas production is often very difficult to forecast due to abnormal GOR's which are typically caused by incorrect gas rate measurements. This paper presents a simple methodology to predict solution gas production based on forecasted oil production. This methodology introduces a new specialized plot which can be used to determine various parameters necessary to forecast solution gas production without any costly PVT and pressure history data. Additionally, this paper presents a step-by-step procedure used to analyze the available history to obtain an accurate representation of GOR performance. This data in turn can be used to predict solution gas production. Missing data and/or incorrect gas measurements are common issues that can directly affect a well's GOR history. The methodology presented in this paper will outline the steps required to repair this kind of bad data and ultimately generate a reasonable GOR forecast that is representative of a well's true performance. This methodology was initially validated using synthetic data (generated by a commercial simulator) and has been subsequently tested on over one thousand oil wells that are producing from tight formations such as the Bakken, Niobrara and Wolfcamp in the USA and the Cardium in Canada. Each test was carried out by hindcasting – using the early part of production data to history-match the later part of history. This methodology has consistently resulted in good agreement between the forecast and the real field data. A number of practical examples from different reservoirs have been presented in this paper to illustrate/validate this new methodology.
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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 | 0.001 | 0.002 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".