Existing Ambiguities in the In-Situ Stresses Determination by Hydraulic Fracturing

Determination of the horizontal stresses in rocks by hydraulic fracturing (HF) method is very common today and can be used in almost any rock formation. The HF method involves the pressuring of a borehole interval that is sealed off by packers, until a fracture occurs or a pre-existing fracture starts to propagate, when the tensile strength of the rock is exceeded. The classical interpretation of HF test data in terms of the in situ principal stresses assumes that rock is linearly elastic, isotropic and homogeneous, and that the pore-fluid effect on rock strength obeys Terzaghi's effective stress law. Despite twenty five yearsof experience during which hundreds of HF stress tests have been performed, there are several importantissues that have not yet been satisfactorily addressed. In this paper, the existing uncertainties are gathered then some summaries and suggestions are expressed about relevance between breakdown pressure and the maximum horizontal stress.

کلیدواژه ها:

In-Situ Stresses ، Hydraulic Fracturing ، Breakdown Pressure