Practical Application Of Non-Newtonian Transient Flow Analysis

Abstract

Abstract Recent studies on the transient flow of non-Newtonian fluid in porous media have proposed new well test analysis techniques for non-Newtonian injection wells. This paper extends these new techniques to non-Newtonian injection well falloff testing. The practical use of this well test analysis method is practical use of this well test analysis method is demonstrated. The limitations of the techniques also are addressed. Examples of field data are used to demonstrate how this analysis can aid in well test interpretation and provide data and insight for the design and operation of enhanced oil recovery projects. projects Introduction The transient pressure behavior in wells receiving non-Newtonian fluids is of considerable interest because of the large number of enhanced oil recovery projects now in operation. As a result of a number of studies over the past 2 or 3 years, an increased understanding of non-Newtonian fluid behavior in petroleum reservoirs has been obtained. It is generally believed that most of the non-Newtonian fluids used in enhanced oil recovery processes are pseudoplastic in nature and their processes are pseudoplastic in nature and their rheology can be approximated by a power-law model. Pressure falloff testing is probably the most common well testing method. This is true particularly when tertiary recovery projects are being particularly when tertiary recovery projects are being considered or are in progress. When injection wells receive expensive fluids like polymer solutions, micellar solutions, and surfactant solutions, their ability to accept these fluids uniformly for a long period of time is important to the economics of the period of time is important to the economics of the tertiary recovery project. The mobilities of these fluids are important parameters in flood design. Also, wellbore damage must be monitored and corrected. Refs. 1 and 2 provide detailed studies of the theory behind the non-Newtonian flow model to be used in this paper. These references also present new well test analysis techniques for non-Newtonian injection well pressure-buildup testing. The purpose of this paper is to extend this analysis to non-Newtonian injection well falloff testing, provide necessary engineering forms for use of the non-Newtonian flow results, and illustrate applications. FALLOFF TEST ANALYSIS The principles of superposition enable us to analyze changing rates of flow from the solution of a constant terminal rate case. The partial differential equation describing the flow of a slightly compressible power-law fluid in an ideal radial system is given in dimensionless form as (1) where (2) (3) (4) and (5)