Two subsea wells completed in first phase of offshore CCS project

Overview

Halliburton 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 into the atmosphere, which could occur if materials used during well construction are not selected carefully. For example, the formation of carbonic acid (H₂CO₃) due to the mixing of dry CO₂ and saline formation water can lead to corrosion of carbon steel, potentially having a 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

Several factors were considered to help ensure the safe and permanent storage of CO₂ during well construction. These included the composition of the injected CO₂, anticipated reservoir pressure evolution, and well temperature variations during injection and shut-in. Additionally, the composition of formation fluids and previous knowledge gained from other CO₂ injector wells were considered. Laboratory corrosion testing determined that tubular 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-in. XtremeGrip® low equivalent circulating density (ECD) and 9 5/8-in. XtremeGrip Quick Lock liner hanger were installed, and sand control was achieved using standalone sand screens (SAS) in the openhole section. For the well's lower completion, 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-in. Opsis® gauges, and the SP™ tubing-retrievable safety valve to ensure safety.

The contingency injector was completed similarly. A 14-in. 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-in. Opsis gauges, and the SP tubing-retrievable safety valve.