Horizontal Well Design Optimization: A Study of the Parameters Affecting the Productivity and Flux Distribution of a Horizontal Well

With the widespread applications of horizontal wells and its successful performance in the last decade, a number of relevant questions has been raised with respect to the optimization of horizontal well design. Considering the high costs involved and the technical challenges that are faced by the industry under various scenarios such as offshore environment, unconsolidated sands and heavy oil production, questions related to the optimization protocols to be followed have become progressively more important and more difficult to answer. Thus, the task of optimizing horizontal well design requires an investigation of the parameters that affect the productivity and ultimately the behavior of both reservoir and horizontal well domains, as well as the risks and costs involved in each alternative. Based on a fully implicit, three-dimensional numerical model coupling reservoir and horizontal well flow dynamics, a detailed study of the parameters that affect the behavior of flux distribution and productivity along horizontal wells has been performed. The parameters analyzed include permeability, initial gas saturation, anisotropy ratio, well location, fluid viscosity, flow rate, well length, and well diameter. A tool that permits to compare and select the potential options in terms of the gain in productivity per additional unit of well length and diameter is also introduced. Validation of the numerical model used in this study is performed using production-logging data and the examples of results of the application of the optimization protocol developed are reported for some of the Petrobras offshore fields.