The In Salah CCS project in central Algeria is a world pioneering onshore CO2 capture and storage project which has built up a wealth of experience highly relevant to CCS projects worldwide. Carbon dioxide from several gas fields is removed from the gas production stream in a central gas processing facility and then the CO2 is compressed, transported and stored underground in the 1.9km deep Carboniferous sandstone unit at the Krechba field.Injection commenced in 2004 and since then over 3.8Mt of CO2 has been stored in the subsurface. The storage performance has been monitored using a unique and diverse portfolio of geophysical and geochemical methods, including time-lapse seismic, micro-seismic, wellhead sampling using CO2 gas tracers, down-hole logging and core analysis, surface gas monitoring, groundwater aquifer monitoring and satellite InSAR data. Routines and procedures for collecting and interpreting these data have been developed, and valuable insights into appropriate Monitoring, Modelling and Verification (MMV) approaches for CO2 storage have been gained.We summarize the key elements of the project life-cycle and identify the key lessons learned from this demonstration project that can be applied to other major CCS projects, notably:The need for detailed geological and geomechanical characterization of the reservoir and overburden;The importance of regular risk assessments based on the integration of multiple different datasets;The importance of flexibility in the design and operation of the capture, compression, and injection system.The in Salah project thus provides an important case study for knowledge transfer to other major CCS projects in the planning and execution phases. (C) 2013 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license.

The In Salah project in Algeria is an industrial-scale CO2 storage project in operation since 2004. Carbon dioxide from several gas fields with a CO2 content of 1-10% is removed from the production stream to meet the export specification of 0.3% CO2. It is re-injected it into a 20m thick fractured sandstone formation down-dip of the Krechba producing field at a depth of around 1850m. There are currently three horizontal injectors at Krechba, injecting up to 50mmscfd of CO2 and drilled perpendicular to the dominant fracture orientation to maximize injection capacity. Over the life of the project it is planned to store up to 17 million tonnes of CO2 - to date, just over 3 million tonnes of CO2 have been injected. A Joint Industry Project (JIP) was set up in 2005 to monitor the CO2 storage process using a variety of geochemical, geophysical and production techniques over a 5 year period.A pre-injection risk register was prepared as part of the initial assessment of the injection site which was used to design the original monitoring programme. Key risks identified included leakage from old wellbores and possible vertical leakage through the overburden. Four years after injection start up, a quantitative risk assessment was undertaken which identified wellbore integrity and potential migration of CO2 out of the licensed storage area as the key risks which resulted in further changes to the forward monitoring programme. A data collection programme was initiated prior to the start of injection in August 2004. A number of monitoring technology reviews have been conducted over the last 5 years using detailed modeling and a Boston Square which has been invaluable in comparing the relative cost and value of quite diverse technologies.To date, with the exception of the CO2 encountered in the old KB-5 appraisal well (now fully decommissioned), there has been no indication of any CO2 moving out of the storage complex (comprising the injection zone and the immediate overburden). The suite of technologies to be deployed at any CO2 storage site for monitoring and verification purposes is readily available and uses mainly standard oilfield techniques and practices. However, each site will require a site specific suite of cost effective and focused technologies to provide the maximum benefit -there is no ` cookie cutter' approach when it comes to designing a Monitoring and Verification programme. Our experience at Krechba to date is only in the early phases of a programme which could extend for 20 years and our key conclusions from the first 5 years of monitoring will be presented. (C) 2011 Published by Elsevier Ltd.

Interferometric Synthetic Aperture Radar (InSAR) data, gathered over the In Salah CO2 storage project in Algeria, provide an early indication that satellite‐based geodetic methods can be effective in monitoring the geological storage of carbon dioxide. An injected mass of 3 million tons of carbon dioxide from one of the first large‐scale carbon sequestration efforts, produces a measurable surface displacement of approximately 5 mm/year. Using geophysical inverse techniques, we are able to infer flow within the reservoir layer and within a seismically detected fracture/fault zone intersecting the reservoir. We find that, if we use the best available elastic Earth model, the fluid flow need only occur in the vicinity of the reservoir layer. However, flow associated with the injection of the carbon dioxide does appear to extend several kilometers laterally within the reservoir, following the fracture/fault zone.

The In Salah project in Algeria is an industrial-scale [Formula: see text] storage project that has been in operation since 2004. [Formula: see text] from several gas fields, which have a [Formula: see text] content of 5–10%, is removed from the production stream to meet the sales gas-export specification of 0.3% [Formula: see text]. Rather than vent that separated [Formula: see text] to the atmosphere (as was normal industry practice for such gas plants), BP and its joint venture (JV) partner, Sonatrach, invested an incremental US$100 million in a project to compress, dehydrate, transport, and inject that [Formula: see text] into a deep saline formation downdip of the producing gas horizon. Statoil then joined the JV at production start-up in August 2004.

Concerns about climate change and the need to stabilize atmospheric CO2 concentrations are driving the development of a lower carbon future. Within this context, carbon dioxide capture and storage (CCS) is gaining momentum as a large-scale option to reduce greenhouse gas emissions. This paper reviews the rationale and potential scale of CCS, the status of geological storage options and lessons from the operating In Salah project. CCS is expected to have applications in the oil and gas industry, and other industries, particularly the coal and power sectors. CO2-enhanced oil recovery, depleted oil and gas fields and saline formations are considered the most important geological storage options. Experience with geological storage is being gained at the In Salah project in Algeria. Operating since 2004, it is the world's first industrial-scale project storing CO2 in the water leg of a gas reservoir. A key challenge for wider deployment is for geological storage to be accepted as a safe and effective option, providing long-term CO2 containment, with high integrity. This has several associated technical and regulatory challenges, including site characterization and selection, geological and well integrity risk assessment, performance prediction, the design of appropriate monitoring schemes and handling the closure and post-closure phases. The petroleum industry has the capabilities and know-how to deploy CCS and to manage the associated risks. This lends confidence that CCS will be a viable option and that deployment will help enable a low-carbon future.

The Krechba field is one of several gas fields located in the Algerian Sahara desert, and was set in operation in August 2004 as part of a joint venture with BP, Sonatrach and StatoilHydro. The natural gas in the fields contains up to 10% CO2, which has to be reduced to 0.3% before the gas is sold, resulting in the production of around 1 million tonnes/year CO2. Rather than vent the CO2 to the atmosphere (business as usual), it is re-injected into the water leg of the Krechba Carboniferous Sandstone gas producing reservoir (20 m thick) via three horizontal wells at a depth of around 1,900metres. CO2 injection started in August 2004 and to date nearly 2.5 million tonnes of CO2 have been injected, amounting to approximately 25% of the gas extracted from the Krechba field over the same period.A number of key technologies to monitor the injection, and the subsurface movement and storage of CO2 have been, and will continue to be, deployed to provide long term assurance of sequestration. Time lapse satellite images (using PSInSAR (TM) Technology) which measure ground deformation to assess the movement of CO2 in the subsurface have proven to be much more successful than initially thought, despite the depth of injection and the low voidage replacement rate (25%). Satellite images collected since start of injection show clear increases in ground elevation of up to 30mm around the three injectors while subsidence is also apparent in the area of maximum gas production. The images have also confirmed the CO2 is moving in the direction of preferred fracture orientation at reservoir level. Recent downhole pressure measurements in one of the injectors also indicates that the CO2 is being contained within the injection horizon. Work is ongoing to integrate the satellite images with geomechanical and seismic data to better understand how these images can be used for monitoring of CO2 movement in the subsurface.A key part of the forward monitoring programme will be the acquistion of time-lapse 3D seismic, deployment of tiltmeters and GPS to confirm and calibrate the satellite imagery data, microseismic detectors in shallow boreholes to assess the degree of rock strain and use of shallow wells to monitor the water chemistry in the vadose zone. These will supplement the ongoing tracer, wellhead sampling and satellite imagery data acquistion. This paper shares the latest results of the ongoing CO2 monitoring project. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract CO2 Capture and geological Storage (CCS) is a technology that is available today and that can cost-effectively solve up to a quarter of the global Greenhouse gas (GHG) problem. CCS can be applied to any fixed, point-source of CO2, and will likely be most cost-effective when applied to large sources close to large sinks. While CCS has application in the oil and gas sector (both upstream and downstream), the largest sources of CO2 exist in the power sector. Oil and gas sources are typically less than one million metric tonnes per annum (mmtpa) CO2, whereas power sector sources are typically more than 5mmtpa CO2. Hence a large-scale sequestration project should store in the order of 1mmtpa CO2. Around 30mmtpa CO2 is being injected into EOR projects, mostly in the USA and Canada. Those EOR projects are being managed to recover and re-inject the CO2 (that they have to buy), rather than sequester it - little or no monitoring is carried out for the purpose of assuring CO2 geological storage. As of today, there are only 4 large-scale projects on the planet which sequester anthropogenic CO2 on the 1mmtpa-scale: Sleipner (Norway), In Salah (Algeria), Weyburn-Midale (Canada) and Snøhvit (Norway). Of these the two most significant (in terms of cumulative volume injected and experience of CO2 storage) are Sleipner (which has been in operation for 13 years) and In Salah (5 years). Weyburn-Midale is a CO2 EOR project involving CO2 cycling and monitoring. Although a portion of the cycled CO2 will be permanently stored, the primary objective of the project is to recover EOR oil. Snøhvit is relatively new (starting injection in 2008) and has not yet stored a significant volume of CO2. We focus therefore on the experience from the two large and mature projects Sleipner and In Salah. These two projects both capture CO2 produced during natural gas processing and store CO2 in deep saline formations. For both projects, the storage was part of the integrated Field Development Plan. They were both permitted under hydrocarbon law, and they illustrate significantly different aspects of storage: technical and commercial. Commercial Frameworks The Sleipner project was mainly stimulated by the introduction in 1991 of the Norwegian offshore CO2 tax (~$50/tonne). The project costs (capex and opex) are essentially covered by avoiding this tax and the project has now passed the break even point in the investment cycle. In contrast, the In Salah project was initiated without tax incentives, but as an initiative by the Operators to avoid excessive additional CO2 emissions to the atmosphere. It is however hoped that the project will qualify for CDM credits under the Kyoto Protocol (but those have not been approved to date).

This chapter provides an update on the in Salah gas (ISG) project and the accompanying CO2 storage assurance project, which it is proposed and managed under the umbrella of a joint industry project (JIP). It consists of project management, establishing a project baseline, imaging CO2 migration, well based monitoring, rock/fluid interactions, detecting surface (geologic) seepage, integration and risk assessment, and communications. This CO2 project differs significantly in geological character and storage process from the existing Sleipner and Weyburn monitoring projects and offers an ideal opportunity to gain important additional information on the permanence and safety of CO2 geologic storage. The ISG project provides an important opportunity to study a gas field development project where geological storage at a field scale is employed to mitigate the environmental impact of the produced CO2 stream, which represents—60% of the projects emissions footprint.