Stability of sand arches: a key to sand control
Studies have shown that grain crushing will not occur as readily at reservoir pore pressures as in laboratory tests at atmospheric pore pressure. Nevertheless, it is likely that many of the deep unconsolidated sand formations are at stress conditions close to the crushing failure range. Stress concentrations around the borehole and perforations (i.e., arching) can bring this sand even nearer the crushing range, or into it. If an arch forms and then crushes, it may reform with relieved stresses in the dilatant range (or at the critical constant-volume stress). A sand-consolidation plastic treatment at this stage can provide ample cohesiveness to stabilize the formation sand at a loading in its dilatant range. But, if stresses later increase enough (due to pressure drawdown or other causes) to reach the crushing stress of the sand, the arch will fail. Most or all of the cohesiveness of the sheared sand will be lost, and it can be washed out about as easily as the sand before consolidation. Such a sand, injected so as to achieve dense enough packing to be dilatant, can form a very stable arch, even with a plastic of moderate cohesiveness. (12 refs.)
- Research Organization:
- Pan American Petroleum Corp.
- OSTI ID:
- 5002836
- Journal Information:
- J. Pet. Technol.; (United States), Journal Name: J. Pet. Technol.; (United States) Vol. 22; ISSN JPTJA
- Country of Publication:
- United States
- Language:
- English
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