Hot oiling spreadsheet

TL;DR: In this paper, the authors present a tool for estimating downhole temperatures in terms of analytic formulas, based on the falling film flow in the annulus and started from the transient differential equations so that the effects of the heat capacity of the tubing and casing could be included.

Abstract: One of the most common oil-field treatments is hot oiling to remove paraffin from wells. Even though the practice is common, the thermal effectiveness of the process is not commonly understood. In order for producers to easily understand the thermodynamics of hot oiling, a simple tool is needed for estimating downhole temperatures. Such a tool has been developed that was distributed as a compiled, public-domain-software spreadsheet. That spreadsheet has evolved into an interactive from on the World Wide Web and has been adapted into a Windows{trademark} program by Petrolite, St. Louis MO. The development of such a tools was facilitated by expressing downhole temperatures in terms of analytic formulas. Considerable algebraic work is required to develop such formulas. Also, the data describing hot oiling is customarily a mixture of practical units that must be converted to a consistent set of units. To facilitate the algebraic manipulations and to assure unit conversions are correct, during development parallel calculations were made using the spreadsheet and a symbolic mathematics program. Derivation of the formulas considered falling film flow in the annulus and started from the transient differential equations so that the effects of the heat capacity of the tubing and casing could be included. While this approach to developing a software product does not have the power and sophistication of a finite element or difference code, it produces a user friendly product that implements the equations solved with a minimum potential for bugs. This allows emphasis in development of the product to be placed on the physics.