New finite element models are presented in this paper which describe the pressure response of formation testers. The influences of formation anisotropy, bed thickness, and horizontal and dipping bed boundaries are investigated. The simulator utilizes techniques for grid optimization already used in improving the quality of finite element solutions for stress analysis of elastic solids and structures. Examples are given comparing interpretation results using the simulator against results obtained using prior standard models.
Near-wellbore simulation (NEWS©) permits the investigator to introduce factors into the model in a manner consistent with basic principles of physics. A new analytic model is presented which incorporates some of the new observations from the finite element models, maintains space-dimensional consistency, and decouples the formation anisotropy and fluid compressibility relationship assumed in the development of the classical spherical flow model by Moran and Finklea.1
Observation points placed at strategic locations in the formation and around the wellbore allow investigation of the pressure response of formation testers with multiple-sensor capability.
New techniques are presented for interpreting the pressure response of formation testers. NEWS© is a powerful tool for understanding and predicting the near-wellbore production dynamics of a well. It is anticipated that the simulations will lead to verification of new or existing models and will aid in developing improved tools and interpretation techniques.