Detecting Wellbore Fractures Using Log Data and Drilling Parameters

The knowledge of the location of the fractures crossing the well has a strong technical and economic impact upon drilling, production and reservoir management strategies. Otherwise; in a fractured reservoir the occurrence of mud loss can be considered as a good indicator of the presence of natural permeable fractures. Most of the techniques currently used for natural fracture detection and localization do not clearly differentiate between fractures that allow fluid flow and those that do not because they do not measure fluid flow properties directly. Core analysis, for example can clearly identify the fractures but is unable to discriminate between minor and isolated fractures from the ones having high permeability. In the same way image logs can accurately locate the presence of fractures but are unable to discriminate between open and closed fractures. Technologies such as imaging log coupled with micro fracture analyses of conventional cores with optical microscopy, NMR, MRI, and tomography have greatly enhanced the possibility of measuring the fracture geometric characteristics. However; the fracture hydraulic width and permeability can only be evaluated from dynamic data revealing production or adsorption along the wellbore. This paper first tries to introduce different methods of mud loss analysis of wellbore fractures detection. Dynamic data was used then to investigate wellbore fracture network (or a single fracture) existence in a well of an Iranian field using a new mud loss analysis model and special type curves.

Keywords:

Naturally Fractured Reservoirs , Mud Loss , Wellbore Fractures , Quantitative Analysis , Drilling parameters