Reservoir Drilling and Completion Best Practices: Well Productivity Assessment Applying Drill in Fluid, Chelant/Enzyme Breaker System and Stimulation Design on Onshore Well BHT Scenario in Brazil

Abstract

A significant number of horizontal wells have ultimately proven to be engineering failure impacting the productivity result negatively. This paper will discuss an approach of a suitable non-damaging fluid designed to drill a depleted and high BHT (Bottom Hole Temperature) horizontal well located on the Sergipe Basin, Northeastern Brazil. Particularly, the application of a customized Chelant /Enzyme filter cake Breaker System and potential Formation of emulsion was evaluated presenting results here. The performance of the fluid loss and viscosifier additives was then evaluated for high BHT. Finally, the necessity of the use of emulsion preventer was evaluated, since tests showed emulsion formation between RDF fluid loss and reservoir oil. The last step was to formulate RDF Breaker. These wellbore productive fluids are designed to attack specific RDF mudcake components; an enzyme and a chelant with the functionality to consume the starch and calcium carbonate components, respectively, minimizing reservoir damage. The results show that the temperature stabilizer displays favorable interactions with polymers when exposed to high temperatures, above 240 °F. The hydroxypropyl starch was selected as the fluid loss controller because it presented lower API filter volume under conditions of 243 ° F for 48h. Under the same conditions between the xanthan gum analyzed for the viscosifying additive, one showed better rheological results. An emulsion preventer selected displayed good results in the action against formation of emulsion of the API filter and the oil. Breaker effectiveness was proven with the Return Permeability Test performed, which showed acted as a mudcake remover formed by the RDF.