A technique based on a simple compressibility equation and a mass balance equation has been developed that allows accurate determination of fracture volume and closure pressure. This new technique may help resolve the controversial determination of when a fracture closes. Through the graphical representation of this technique, knowledge of the fracture closure mechanism has been gained and presented in this paper.

The presented technique may be applied to either microfracture or minifracture tests. It may be applied to a pump-in/flowback test (microfracture) or be coupled with the conventional minifracture analysis technique for application to pump-in/shut-in tests.

The new technique is illustrated in this paper through its application to actual field cases. In the first field case, it is applied to a microfracture test (pump-in/flowback) performed on a shale formation. The technique clearly identified the closure pressure of the fracture and the fracture volume, and fluid efficiency was calculated using an iterative scheme. In the second example, the technique was applied to a minifracture test (pump-in/shut-in).

The chief technical contributions of this paper may be summarized as follows:

  1. A simple new technique is presented for determining fracture volume and closure pressure.

  2. Through the graphical representation and application of the new technique, a better understanding of the closure mechanism has been achieved.

  3. This technique determines fracture closure pressure with a fairly high degree of certainty.

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