Abstract

When a hydraulically fractured oil well, with a single vertical fracture, does not respond favorably to the stimulation treatment, and provided that well conditions warranted the frac treatment, the cause of poor response is due to flow restrictions within the propped fracture, an unpropped fracture, or a damaged region in the formation adjacent to the face of a propped fracture. By the proper analyst of pressure buildup data taken from the we pressure buildup data taken from the we location of the flow restriction can be determined. Linear flow into the fracture distinguishes formation damage from either an unpropped fracture or from restrictions in a propped fracture. Approximations of the propped fracture. Approximations of the fracture length and thickness of the damaged region near the fracture face are available by using the techniques presented.

Introduction

The production performance of an oil well following a hydraulic fracturing treatment often continues on pre-stimulation decline trends, does not return to prior levels, or improved rates are not sustained. Providing that well conditions warranted the fracture stimulation, the causes of the unfavorable results are either due to flow restrictions within the propped fracture, an unpropped fracture, or a damaged region in the formation adjacent to the face of a propped fracture.

When the fracture is vertically oriented and when negligible or zero flow occurs in the fracture, the fluids flow radially into the wellbore from the surrounding formation. If the formation near the fracture face is damaged, then the flow near the propped fracture is essentially linear. Thus, recognition of the type of flow near the well determines the condition causing reduced flow rates, i.e., either 1) plugged propped fractures or unpropped fractures, or 2) formation damage adjacent to the propped vertical fracture.

A method is presented herein for the identification of the flow regime near the well from pressure buildup data. Approximations of the fracture length and thickness of the damaged region near the fracture face are available by using the techniques presented.

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