ABSTRACT

The development of combination products for scale and corrosion inhibition for wells producing at high downhole temperatures (~150°C) and that generate produced waters with high calcium concentrations can be a challenging undertaking. Traditional phosphonate scale inhibitors can be very effective; however, they have been shown to form insoluble precipitate, “pseudo scale”, at high calcium concentrations that can plug and fail capillary strings. The development in this work considered the use of polymeric type scale inhibitor and a new high temperature corrosion inhibitor. Additionally, the evaluation of the corrosion performance is challenging due to the difficulties derived from attempting to prevent the scaling process while trying to obtain meaningful corrosion performance data. The developed combination product was stable at 150°C, compatible with capillary string materials, and outperformed an incumbent product based on a phosphonate scale inhibitor and a traditional corrosion inhibitor.

INTRODUCTION

The development of combination products for scale and corrosion inhibition for wells with high downhole temperatures, about 150°C (302°F), with produced waters containing high Calcium concentrations can be a challenging undertaking. Traditional phosphonate scale inhibitors can be very effective at high temperatures; however, they have been shown to form insoluble inorganic scales at high calcium concentrations that can plug and fail capillary strings1,2. The development in this work considered the use of non-phosphonate polymeric type scale inhibitors and a new high temperature corrosion inhibitor to replace an incumbent phosphonate based combination product.

Because this is a high temperature application, the evaluation of the corrosion performance is challenging due to accelerated scale formation at elevated temperature. This scale formation causes inconsistencies in the results of the corrosion performance tests3,4,5. To alleviate the scale formation experienced at high temperature, increased amounts of scale inhibitor were added to untreated corrosion tests, which establish a baseline for maximum corrosion, and tests with corrosion inhibitor components to make the corrosion performance assessment possible. The product development resulted in several products that matched or improved the performance of the previous generation high temperature-compatible product while eliminating the possibility of pseudo scale formation.

This content is only available via PDF.
You can access this article if you purchase or spend a download.