The Petrophysical Evaluation of the Haynesville Shale and its Application to Hydraulic Fracture Design
The Late Jurassic Haynesville Shale is an unconventional, overpressured gas reservoir located in northeastern Texas and northwestern Louisiana. Relatively high natural gas prices and recent successes in other shale gas plays have led a number of operators to invest significantly in the Haynesville. It has great potential for development by applying all the new technology currently available in the oil and gas industry.
Petrophysical evaluation of reservoirs has long been used for exploration and reserves estimates. New logging tools and analysis techniques have been developed to provide more precise data about target zones and bounding layers that are important when considering hydraulic fracturing for unconventional reservoirs. A processed log interpretation calibrated for the Haynesville shale is computed using a typical triple combo suite of logs. Other log data such as borehole imaging, magnetic resonance, dipole sonic, and spectral gamma ray are used to improve and verify the interpretation. Core samples provide essential data on mineralogy, TOC, and rock mechanical properties to further calibrate this processed log computation and improve the accuracy of the total shale interpretation.
Identification of the following reservoir characteristics provides the starting point for completion and hydraulic fracture stimulation design: a) identification of free gas zones, b) identification of rock types and mineralogy, c) TOC, d) quantification of effective shale porosity, e) estimates of shale permeability, f) mechanical stress measurement, and g) identification, classification, and orientation of marginal class, open conductive, and drilling-induced fractures. A number of Haynesville Shale examples will be presented to highlight the interpretation techniques and variations in the shale itself within its proven productive area. This interpretation can be critical for the hydraulic fracture design approach used on the Haynesville Shale.