Bibliographic record
Abstract
Abstract A tight gas reservoir is commonly defined as a reservoir having less than 0.1 millidarcies permeability. There are several basic concepts and field cases of different well tests in tight gas reservoirs in the literature, but not presented as a general guide. In this paper, we gather valuable information and provide a useful guide to the most important well tests in tight gas reservoirs. Generally due to low permeability of these reservoirs, a well will not flow initially at measurable rates and conventional well testing cannot be applied. Therefore, fracture stimulation must be considered. Many authors present procedures for design of pre and post-frac tests. The pre-frac test permits calculating preliminary estimates of reservoir permeability and initial pressure. Because of economic and environmental reasons, short duration procedures are of interest. Hence, prime candidates are pre-frac, short time, small volume, closed chamber tests. These tests have to be analyzed by special methods to provide improved values of reservoir parameters. In this study, we also present a review of some aspects in tight gas well testing like pressure-dependent permeability, estimation of pseudo-time at the average pressure of the region of influence, supercharge effect, the problem of treating the pressure-dependent product µct during pre-frac test analysis and the concept of instantaneous source response Introduction Large decreases in production and increases in demand for fossil-fuels cause the economic gas production from unconventional resources (tight gas, coal bed methane (CBM), and gas hydrate) to be a great challenge. Huge reserves, longterm potential, low gas prices and some other factors account for the great influence of these resources on the future of energy. There is no formal definition for "Tight gas". Commonly used definition, describes tight gas reservoirs as those having permeabilities less than 0.1 millidarcies. Recently, the German Society for Petroleum and Coal Science and Technology (DGMK) defined tight gas reservoirs as those with average effective gas permeability of less than 0.6 mD. "Ultra tight" gas reservoirs may exhibit permeabilities down to 0.001 mD. To improve the recovery of this resource, GFREE [1] research program has been created at the University of Calgary. GFREE [1] stands for:Geoscience aspects (G)Formation evaluation by petrophysics and well test (F)Reservoir drilling, completion and stimulation (R)Reservoir Engineering (RE)Economics and long run supply curves (E) As a part of the activities of this research program, we have concentrated on Formation evaluation (F) by well testing, and conducted a literature survey which is presented in this paper. Well testing is generally done to estimate hydrocarbon (here gas) in-place and recoverable resources. Initial pressure is a critical parameter not only for estimating gas in-place, but also for determining how much field development is required and whether or not the field is overdeveloped. In addition to pi, well testing provides an estimate of permeability. A problem associated with well testing in tight gas sands is that usually long times are required to reach redial flow, due to their extremely low permeabilities.
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 | 0.000 | 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 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".