Success of acid fracturing treatment depends greatly on the created conductivity
under closure stress. In order to have sufficient conductivity, the fracture face must be
non-uniformly etched while the fracture strength maintained to withstand the closure
stress. While there have been several experimental studies conducted on acid fracturing,
most of these have not scaled experiments to field conditions and did not account for the
effect of rock weakening and etching pattern. Hence, acid fracture conductivity
predictions based on the above works have not been able to match actual results.
In order to develop a more appropriate and accurate prediction of acid fracturing
treatment outcome, a laboratory facility was developed that is properly scaled to field
conditions and enables analysis of etching pattern and rock strength. A systematic
experimental study that covered a variety of formations, acid types, and acid contact
times was conducted. An acid fracture conductivity correlation was developed based on
etched volume, etched pattern, and fracture strength under closure stress.
Results suggested that there is an optimal time of acid exposure resulting in
maximum fracture conductivity. There were large differences in the conductivity created with the different acid systems tested due to different etching patterns and degree of rock
strength weakening. There was an optimal acid system depending on formation type,
contact time and overburden stress. The acid fracture conductivities measured did not
agree with the predictions of the Nierode-Kruk correlation. The newly developed
correlation predicts conductivity much closer as it includes the effect of rock strength
and surface etching pattern on resulting conductivity.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2361 |
| Date | 15 May 2009 |
| Creators | Pournik, Maysam |
| Contributors | Hill, A. Daniel |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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