While fracture models can define geometric complexity of hydraulic fractures that result from such things as lithology, rock mechanical properties, and stress magnitude and direction, confirmation of the actual geometry achieved is still required to apply the models with confidence. This is being accomplished through the use of acoustic-based techniques that offer a better understanding of the specific features of the fracture geometry and to optimize treatment at each stage.

Evaluating fracture geometry is critical during treatment execution and for subsequent design improvement. The methods for evaluating fracture geometry during and after fracture creation are classified into near-wellbore and far-field methods and is based on the depth of investigation of the tool used to collect data.

A differential cased-hole sonic anisotropy model is in use for larger casing diameters, but until now there has not been a method for use in small-diameter holes such as in tight gas reservoirs. To obtain the benefits of a detailed sonic investigation in smaller boreholes, a slimhole tool has been developed to monopole and cross-dipole sonic logging—the ThruBit Dipole though-the-bit acoustic service. The service, contained in a 2 1/8-in-OD housing, generates high-quality dipole measurements that have been confirmed in a variety of borehole and formation conditions, including cased-hole wells. This extension of cased-hole sonic anisotropy to the logging of small casing diameters, the ThruBit Dipole service enables comparing post-fracture slim dipole log or openhole log data from the full-size Sonic Scanner acoustic scanning platform.

Read the World Oil article here.