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Title: Geomechanical evaluation of a poorly consolidated sandstone with applications to horizontal drilling, borehole stability, reservoir compaction, and sand control
Author: Skopec, Robert A.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2002
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Decreasing strength with increasing effective compressive strength, referred to as "cap" behavior is often attributed to pore collapse and a reduction in pore throat apertures during early drawdown. Over-consolidation with only a slight increase in effective stress creates secondary fine particles that leads to formation damage and permeability decline. Grain crushing and the creation of a secondary fines population exacerbates pore blockage that results from mobilization of loosely attached kaolinite or other non-load bearing fine particles. Pore volume compressibility data indicate that compaction effects are significant and pose a potentially serious production problem during depletion. Pore volume lost during depletion is non-recoverable and will not "rebound." Re-injection of water will not re-establish the pore volume lost during compaction as a result of reservoir depletion. Compressibility and compaction trends in the Lower Captain Sandstone contradict several petroleum industry theories. Effective confining pressure and effective mean stress were higher under uniaxial strain boundary versus triaxial conditions and play a greater role in compaction than shear stresses. Captain pseudo shales exhibit strain-softening behavior and peak strengths are quite close to residual strengths. Captain pseudo shales clearly have residual load-bearing capacity and strain-softening promotes plasticicity.  Use of standard core analysis methods to measure pore volume compressibility and fines migration potential are highly discouraged in unconsolidated as well as consolidated sandstones. Petrographic, mineralogical, and routine petrophysical analyses are essential in the interpretation of rock mechanics data.

Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Petrography Mines and mineral resources Soil science Geology Mineralogy Sedimentology