Two subsea wells completed in first phase of offshore CCS project

Overview

Halliburton successfully delivered a top-to-bottom completion solution for a cross-border CO2 transport and storage facility. Phase I of this project includes the capacity to transport, inject, and permanently store up to 1.5 million metric tons of CO2 per year. CO2 storage will be possible through one injection well, which was sidetracked and completed from the original exploration well and a new contingency well. With these two wells in place, the customer is motivated to drill and complete three additional injection wells to expand capacity by an additional 3.5 million metric tons to a total of 5 million metric tons annually. The expanded capacity will help the customer accelerate industrial decarbonization and provide future CO2 storage options for Europe.

Challenge

The safe and successful design and operation of carbon capture and storage (CCS) wells requires careful consideration of a range of technical challenges. The primary objective is to ensure the permanent sequestration of CO2 underground, which is dependent on the integrity of the well. One challenge is helping prevent leakage of CO2 to the atmosphere, which could occur if materials used during well construction are not selected carefully. For example, the formation of carbonic acid (H2 CO3 ) due to the mixing of dry CO2 and saline formation water can lead to corrosion of carbon steel, potentially having negative impact on well integrity. To help prevent such issues, operators must select materials suitable for the well environment and compatible with the operator’s objectives.

Solution

To help ensure the safe and permanent storage of CO2 during well construction, several factors were considered, including injection CO2 composition, anticipated reservoir pressure evolution, well temperature variations during injection and shut-in, formation fluids composition, and previous knowledge gained from other CO2 injector wells. Laboratory corrosion testing determined that tubulars and completion equipment installed at the bottom of the well should be 25% chrome alloy or superior materials to allow a 25-year well lifetime.

During well construction of the primary injection well, a 14-inch XtremeGrip® low equivalent circulating density (ECD) and 9 5/8-inch XtremeGrip Quick Lock liner hanger were installed and sand control was achieved using standalone sand screens (SAS) in the openhole section. For the lower completion of the well, the Halliburton Versa-Trieve® retrievable sand control packer and FS2 fluid loss control valve were used. The upper completion was finalized using the Halliburton hydrostatic-set Perma-Series® HNT packer, 4 1/2- and 7-inch Opsis® gauges and the SP™ tubing-retrievable safety valve (TRSV) to ensure safety.

The contingency injector was completed in a similar manner. A 14-inch Low ECD liner hanger was installed during well construction and sand control was achieved by gravel packing the openhole section. A Versa-Trieve retrievable sand control packer and FS2 fluid loss control valve were used for the lower completion, and the upper completion consisted of the X-Trieve™ XHHC retrievable production packer, two 7-inch Opsis gauges and the SP TRSV.