Project: In Salah
Company/Alliance: BP, Sontrach and Statoil
Start Date: 2004. Injection was suspended June 2011
Size: 1-1.2 Mt/yr
CO2 Source: Gas processing from In Salah Oil Field (the gas contains approximately 5.5% CO2 at the surface)
Storage: The Krechba Formation: A depleted gas reservoir located near the gas processing plant. The target Formation is a 1.9km deep Carboniferous sandstone unit at the Krechba field. Three long-reach horizontal injection wells were used to inject the CO2 into the down-dip aquifer leg of the gas reservoir.
Total project is estimated to cost US$2.7 billion.
Injection started in 2004 and injection suspended in 2011 due to concerns about the integrity of the seal. During the project lifetime 3.8MT/CO2 was successfully stored in the Krechba Formation. No leakage of CO2 was reported during the lifetime of the project.
The formation has an estimated 17 million tons total storage lifetime. CO2 injection cost approximately $6 /ton CO2. The Krechba storage well at In Salah had a relatively low level of rock permeability compared to oil reservoir rocks for instance and injection was therefore undertaken via 3 long-reach horizontal wells. The successful storage of CO2 in the Krechba Formation gives valuable insight into how CO2 can be stored in analogous carboniferous sandstone wells common in the USA, Northwest Europe and China.
The site has been closely monitored with a variety of monitoring techniques. The pioneering use of satellite InSAR (Interferometric Synthetic Aperture Radar) data was used to monitor ground strains related to subsurface injection pressure and the consequential rock mechanical response in the reservoir and overburden. Time-lapse seismic and micro-seismic data have also contributed valuable new insights into the formation response to CO2 injection. Monitoring data has been used to update and refine the geological, geomechanical and flow dynamical models of the storage complex.
Analysis of the reservoir, seismic and geomechanical data from 2010 led to the decision to suspend CO2 injection in June 2011. The future injection strategy is currently under review and the comprehensive site monitoring programme continues. There were concerns about possible vertical leakage into the caprock led to an intensified R&D programme to understand the geomechanical response to CO2 injection at this site, summarized in the following section.
Project Link: In Salah project website
Other Sources and Press Releases:
In Salah project in detail
BP In Salah project website
SBSTA Meeting Bonn presentation - Iain Wright, BP [PDF] (May 2006)