Stefan Bachu

Leakage of natural gas (mainly methane) along oil and gas wells contributes to fugitive greenhouse gas emissions. Natural gas leakage occurring outside the well casing and cement sheath and reaching the surface, hence the atmosphere, is known as Gas Migration (GM). In this paper an analysis of the occurrence of gas (methane) migration along wellbor...

Prepared by Alberta Innovates ‐ Technology Futures (AITF)

While enhanced oil recovery using carbon dioxide (CO2-EOR) is a mature technology and known to concurrently store large volumes of CO2, it is not currently viewed by industry as a CO2 storage process. Application of CO2-EOR for CO2 storage to reduce anthropogenic CO2 emissions 1) enables carbon capture and storage (CCS) technology improvement and c...

While enhanced oil recovery using carbon dioxide (CO2-EOR) is a mature technology and known to concurrently store large volumes of CO2, it is not currently viewed by industry as a CO2 storage process. Application of CO2-EOR for CO2 storage to reduce anthropogenic CO2 emissions 1) enables carbon capture and storage (CCS) technology improvement and c...

Carbon capture and storage (CCS) is the only viable technology to mitigate carbon emissions while allowing continued large-scale use of fossil fuels. The storage part of CCS involves injection of carbon dioxide, captured from large stationary sources, into deep geological formations. Deep saline aquifers have the largest identified storage potentia...

The Province of Alberta is the largest CO2 emitter in Canada, with annual emissions close to 250 Mt, of which about 55 Mt CO2 originate from oil production from oil sands. Geological storage of CO2 has been identified as the major component of the strategy for reducing greenhouse gas emissions from oil sands operations, which are located in the Ath...

Various approaches are used to evaluate the capacity of saline aquifers to store CO2, resulting in a wide range of capacity estimates for a given aquifer. The two approaches most used are the volumetric “open aquifer” and “closed aquifer” approaches. We present four full-scale aquifer cases, where CO2 storage capacity is evaluated both volumetrical...

Geological Storage of CO2 has been identified by the provincial Alberta government as the major component of its strategy for reducing greenhouse gas emissions in the province. The issue of reducing atmospheric CO2 emissions is particularly important for oil sands plants, whose emissions in 2013 were in the order of 55 Mt CO2eq. Unfortunately, the...

Increasing oil production from the bitumen deposits in Alberta requires lowering the CO 2 footprint of the oil sands plants. These deposits are located at the shallow edge of the Alberta basin where no CO 2 storage potential exists. The Devonian formations located to the west of these deposits contain multiple saline aquifers and hydrocarbon reserv...

A 3-year binational effort between the United States and Canada was initiated to characterize the lowermost saline system in the northern Great Plains–Prairie region of North America and determine its CO2 storage capacity. This saline system covers an area of 1.34 million km2 from northern South Dakota in the United States to central Alberta and Sa...

One of the most important mechanisms for CO2 storage in deep saline aquifers is CO2 trapping at irreducible saturation, which depends on the relative permeability characteristics of CO2/brine systems. CO2 injectivity, pressure build-up and the evolution and long-term fate of the injected CO2 also depend on the same relative permeability characteris...

In the area underlain by the Basal Aquifer in the Prairie region of Canada, there are 20 large CO2 sources (coal-fired power plants, oil sands and heavy oil production and upgraders, refineries, chemical and petrochemical plants, fertilizer plants and cement plants) that emit more than 1 Mt CO2/year each, for a total of 83 Mt CO2/year,which represe...

Planning by policy makers, and industry and regulatory agencies for underground CO2 storage requires an assessment of the interaction of CO2 storage operations with other subsurface resources, so that the economics, impacts and risks associated with the geological storage of CO2 can be properly assessed. We provide guidance on the potentially benef...

In this presentation, we review the current state of knowledge on wellbore integrity as developed in the IEA Greenhouse Gas Programme's Wellbore Integrity Network. Wells are one of the primary risks to the successful implementation of COâ storage programs. Experimental studies show that wellbore materials react with COâ (carbonation of cement and c...

The Heartland Area Redwater CO2 Storage Project (HARP) is a staged CO2 storage project located near Edmonton in the industrial heartland of Alberta, Canada. The project, being developed by ARC Resources Ltd. of Calgary, aims to store CO2 captured from diverse sources into the very large Redwater Leduc Fm. carbonate reef situated at depths between 9...

The efficiency of Carbon Capture and Storage (CCS) projects is directly related to the long term sealing efficiency of barrier systems and of wellbore cement in wellbores penetrating storage reservoirs. The microfractures inside the wellbore cement provide possible pathways for CO2 leakage to the surface and/or fresh water aquifers, impairing the l...

Prepared by Alberta Innovates-Technology Futures (AITF) for Enhance Energy Inc.

Carbon dioxide storage in geological media is a climate change mitigation technology that is based on the ability of certain geological media to retain CO2 in supercritical phase or dissolved in formation water and to prevent its return to the atmosphere for very long periods of time. However, in certain cases there are flow pathways, natural or ma...

Carbon capture and geological storage (CCS) operations will require an environmental risk analysis to determine, among other things, the risk that injected CO2 or displaced brine will leak from the injection formation into other parts of the subsurface or surface environments. Such an analysis requires site characterization including identification...

Résumé — Variations de pression au cours de l'injection de gaz acides dans le réservoir récifal du champ de Zama, Canada. Implications pour le stockage géologique de CO 2 — Le but de l'article est de comprendre l'accroissement de pression dans le gisement de Zama X2X, utilisé pour le stockage de gaz acide (NO de l'Alberta, Canada), et aussi d'exami...

A review is presented of the factors considered important in the selection of environments and sites for the geological storage of carbon dioxide (CO2) and the disposal of radioactive waste (RW)—with a focus on those of a geological nature. The distinction between the terms storage for CO2 and disposal for RW is not significant in this regard. The...

Screening of potential sites for CO2 storage, site selection and site characterisation are important first steps in the process of implementation of CO2 storage projects. Sites must meet a series of criteria that reduce to the following fundamentals: a site must have the necessary capacity and injectivity to accept the intended volume of CO2 at the...

Carbon dioxide capture and geological storage is a climate change mitigation strategy that will deliver a significant reduction in carbon dioxide atmospheric emissions. There is political consensus around the urgent need to prove this technology on a large scale and to address concerns the public may have about safety. At the same time, the science...

Proper modeling of the multiphase flow of supercritical CO2 in deep saline aquifers for CO2 sequestration (both cycles of drainage during injection and imbibition during CO2 migration) is critical in being able to understand and predict both the short and long term fate of the injected CO2 over extended time periods (hundreds to thousands of years)...

Canada's federal and provincial governments have announced significant financial support for the implementation of a number of large-scale CO2 capture and storage (CCS) demonstration projects in western Canada. One of the demonstration projects that has received federal and provincial funding is the Heartland Area Redwater Project (HARP). The HARP...

Hydrogen sulfide breakthrough in producing wells occurred after the breakthrough of CO2 in the Long Coulee Glauconite F reservoir in southern Alberta, where acid gas (98% CO2, 2% H2S) has been injected since 2002. It was hypothesized that the preferential solubility of H2S in formation brine is responsible for the delay in H2S breakthrough. To stud...

A series of laboratory experiments were carried out to examine the chromatographic partitioning of impurities contained in a stream of CO2 injected into a deep saline aquifer. The experiments were carried out under static (no flow) and dynamic conditions, mainly with H2S as the impurity in the CO2 stream, for 2%, 5% and 30% concentrations, and for...

Laboratory experiments reported in a companion paper were carried out to examine the chromatographic partitioning of impurities contained in a stream of CO2 injected into a deep saline aquifer. The solubility of the impurity gas in the CO2 stream compared to that of CO2, the in situ conditions of pressure, temperature and water salinity, and the co...

Two sets of experiments on typical Class G well cement were carried out in the laboratory to understand better the potential processes involved in well leakage in the presence of CO2. In the first set, good-quality cement samples of permeability in the order of 0.1 μD (10−19 m2) were subjected to 90 days of flow through with CO2-saturated brine at...

Purpose The purpose of this paper is to identify and characterize a geological storage site at more than 800 m depth that is capable of storing large quantities of carbon dioxide (CO 2 ) in the Alberta Basin and is close to a large CO 2 supply. Design/methodology/approach Five criteria are used to select the site: total volume of the pore space of...

An extensive laboratory program was conducted for the measurement of the interfacial tension between CO2 and water or brine covering the ranges of (2 to 27) MPa pressure, (20 to 125) °C temperature, and (0 to 334 010) mg·L−1 water salinity. The laboratory experiments were conducted using the pendant drop method combined with the solution of the Lap...

Geological storage of carbon dioxide (CO2) is likely to be an integral component of any realistic plan to reduce anthropogenic greenhouse gas emissions. In conjunction with large-scale deployment of carbon storage as a technology, there is an urgent need for tools which provide reliable and quick assessments of aquifer storage performance. Previous...

The Heartland Area Redwater Project (HARP) for CO2 storage is investigating the technical and economic feasibility of injecting significant volumes of CO2 into the large water-saturated portion of a huge Devonian reef that is capped by a comparatively small oil reservoir, nevertheless the third largest oil pool in western Canada. The reef has a tot...

The displacement of brine by CO2 during CO2 injection and migration, and the displacement of CO2 by invading brine in the wake of migrating CO2 depend on the interfacial tension of the CO2-brine system. An extensive laboratory program was conducted for the measurement of the interfacial tension (IFT) between CO2 and water or brine covering the rang...

Acid gas comprising 98% CO2 and 2% H2S has been injected since 2002 in a depleted gas reservoir in Alberta, Canada, that has 20% water saturation. Carbon dioxide broke through first at producing wells, while H2S broke through after CO2. It was hypothesized that the delayed breakthrough of H2S was due to its greater solubility in reservoir water tha...

One of the outstanding challenges for large-scale CCS operations is to develop reliable quantitative risk assessments with a focus on leakage of both injected CO2 and displaced brine. A critical leakage pathway is associated with the century-long legacy of oil and gas exploration and production, which has led to many millions of wells being drilled...

CO2-enhanced oil recovery projects have been the initial areas of focus for advancing geological storage of CO2 as a key greenhouse gas mitigation option. Canada has provided international leadership through the IEA GHG Weyburn CO2 Monitoring and Storage Project. In late 2004, a CO2 EOR flood pilot within the Cretaceous Cardium Formation within the...

Developing countries such as China, India, Mexico and Brazil are major energy producers and users, and emitters of CO2, and these countries are becoming aware of both the need to reduce anthropogenic CO2 emissions into the atmosphere and of CO2 capture and storage (CCS) as an enabling technology. One of the challenges faced in the implementation of...

Wells have been identified as posing a greater risk for leakage from CO2 storage sites than geological features such as faults and fractures, particularly in mature sedimentary basins with high well density such as those onshore in North America. A commonly-held belief is that CO2 injection wells will pose a lesser risk than wells drilled for other...

Implementation of carbon dioxide storage in geological media requires a proper assessment of the risk of CO2 leakage from storage sites. Leakage pathways may exist through and along wellbores which may penetrate or be near to the storage site. One method of assessing the potential for CO2 leakage through wells is by mining databases that usually re...

Assessment of the potential for CO2 leakage from geological storage sites is essential for the implementation of CO2 capture and storage in geological media. Possible pathways for CO2 leakage from a storage site include natural interruptions and breaches through the confining strata, faults and fractures, and degraded wells. Knowledge of the geolog...

A significant number of large CO2 emitters are located in central Alberta, Canada, including four coal-fired power plants in the Wabamun Lake area, with cumulative annual emissions in the order of 30 million metric tons CO2. To help industry and regulatory agencies in selecting and permitting sites for CO2 storage, proper characterization is essent...

The modeling of CO2 sequestration in saline aquifers is becoming increasingly important as this method emerges as the prime technology available for the disposal of large volumes of anthropogenically-generated CO2, thus reducing atmospheric CO2 emissions. The interfacial tension between the saline brine in the aquifer and the injected CO2 phase has...

Impure CO2 containing less than 2% H2S has been injected since 2002 into the depleted Long Coulee Glauconite F gas Pool in southeastern Alberta. Breakthrough was observed within one to three years in producing wells, leading to their abandonment. Simulation studies reported in this paper indicate that additional gas was recovered as a result of CO2...

The modeling of CO2 sequestration in saline aquifers is becoming increasingly important as this method emerges as the prime technology available for the disposal of large volumes of anthropogenically-generated CO 2, thus reducing atmospheric CO2 emissions. The interfacial tension between the saline brine in the aquifer and the injected CO2 phase ha...

Carbon dioxide capture and geological storage (CCGS) is an emerging technology that is increasingly being considered for reducing greenhouse gas emissions to the atmosphere. Deep saline aquifers provide a very large capacity for CO2 storage and, unlike hydrocarbon reservoirs and coal beds, are immediately accessible and are found in all sedimentary...

Disposal of acid gas, composed of carbon dioxide (CO2) and hydrogen sulfide (H2S), in deep underground formations is a means for reducing atmospheric emissions of toxic and greenhouse gases produced from sour-gas reservoirs that has been practiced for 18 years in North America and is currently being considered in other regions, such as the Middle E...

Previous work, presented in SPE 106817, "Evaluation of the Potential for Gas and CO2 Leakage along Wellbores", described a method to predict the potential for wellbore leakage which primarily occurs in the shallow areas of a wellbore. The work presented here focuses on the potential for leakage to occur from the deep regions of a wellbore, particul...

Alberta is the province with the largest CO2 emissions in Canada, with approximately two-thirds of emissions originating from large stationary sources. Due to the fortuitous association of large CO2 sources with the storage capacity offered by the underlying Alberta basin, it is expected that large-scale CO2 geological storage in Canada will occur...

Carbon dioxide capture and geological storage is an enabling technology that will allow the continued use well into this century of fossil fuels, mainly coal, for power generation and combustion in industrial processes because they are relatively abundant, cheap, available and globally distributed, thus enhancing the security and stability of energ...

Hydrogen sulfide breakthrough in producing wells occurred after the breakthrough of CO2 in the Long Coulee Glauconite F reservoir in southern Alberta, where acid gas (98% CO2, 2% H2S) has been injected since 2002, It was hypothesized that the preferential solubility of H2S in formation brine is responsible for the delay in H2S breakthrough. To stu...

Implementation of CO2 capture and geological storage (CCGS) technology at the scale needed to achieve a significant and meaningful reduction in CO2 emissions requires knowledge of the available CO2 storage capacity. CO2 storage capacity assessments may be conducted at various scales—in decreasing order of size and increasing order of resolution: co...

Methodology is presented for a first-order regional-scale estimation of CO2 storage capacity in coals under sub-critical conditions, which is subsequently applied to Cretaceous-Tertiary coal beds in Alberta, Canada. Regions suitable for CO2 storage have been defined on the basis of groundwater depth and CO2 phase at in situ conditions. The theoreti...

The capture and geological storage of CO2 is emerging as a viable option to reduce emissions of greenhouse gases into the atmosphere, and CO2-enhanced oil recovery (EOR) is a potential process for long-term CO2 storage. The safety of CO2 storage is critically important because decision and policy makers, regulatory agencies and the public must be a...

Carbon dioxide has been successfully used in more than 80 enhanced oil recovery (EOR) operations in North America, and the number of such operations may increase significantly around the world if CO2 becomes available at reasonable costs. On the other hand, geological storage in deep saline aquifers and hydrocarbon reservoirs of large amounts of CO...

Associated with the endeavours of geoscientists to pursue the promise that geological storage of CO2 has of potentially making deep cuts into greenhouse gas emissions, Governments around the world are dependent on reliable estimates of CO2 storage capacity and insightful indications of the viability of geological storage in their respective jurisdi...

Carbon dioxide capture from large stationary sources and storage in geological media is a technologically-feasible mitigation measure for the reduction of anthropogenic emissions of CO2 to the atmosphere in response to climate change. Carbon dioxide (CO2) can be sequestered underground in oil and gas reservoirs, in deep saline aquifers, in uneconom...

Implementation of CO 2 storage in geological media requires a proper assessment of the risk of CO 2 leakage from storage sites, particularly through and along wellbores. One method of assessing the potential for CO 2 leakage through wells is by mining databases that usually reside with regulatory agencies for information about the condition of exis...

The mature sedimentary basins of North America have a long history of oil and gas exploration and production. This has resulted in many wells being drilled, with a substantial number of them now abandoned. Therefore, injection and storage of CO 2 in these basins requires analysis of possible leakage along those wells. A computationally fast semi-an...

This paper presents, for the first time, an examination of the carbon dioxide (CO 2) storage capacity resource of a major hydrocarbon province incorporating estimated depletion dates for its oil and gas fields with the largest CO 2 storage capacity. This allows the development of a projected timeline for CO 2 storage availability across the basin a...

Geomechanical parameters such as in-situ stresses, rock stiffness and rock strength have a critical influence on the performance of sites for CO 2 geological storage. Mechanical properties data from the Alberta Basin, Canada, indicate that, on average, confining shales are weaker and softer than reservoir sandstones and carbonates, hence they are m...

Carbon dioxide capture and geological storage (CCGS) from large industrial sources has been identified as one method to avoid the release of large amounts of greenhouse gas (GHG) emissions, specifically CO 2 , to the atmosphere. If CCGS is to play a significant role in GHG abatement, policymakers need to address the appropriate pace and scale of de...

Sequestration of CO2 and H2S (acid gas) in deep underground formations is a means for reducing atmospheric emissions of acid gas produced from sour gas reservoirs that has been practiced for 15 years in North America and that is currently being considered in other regions such as the Middle East and central Asia. Furthermore, acid-gas injection ope...

Stefan Bachu is senior advisor for Energy and Carbon Management Geoscience in the Alberta Geological Survey, Alberta Energy and Utilities Board. During his career, he has been involved in various research activities related to the subsurface flow of fluids and heat, with application to the Western Canada sedimentary basin. For more than a decade, S...

Injection of CO2 has been used for EOR in many light and medium gravity reservoirs. Consequently, sequestration of CO2 in oil reservoirs in conjunction with CO2-EOR is a method that is under consideration for reducing CO2 emissions into the atmosphere. Brine-CO2 interfacial tension (IFT) measurements were conducted for equilibrium brines and CO2 at...

Sequestration of CO2 in deep saline aquifers is a means with great potential for reducing emissions of this greenhouse gas produced from a wide range of industrial operations. The displacement characteristics of CO2 injected into deep saline aquifers are essential in that they control both the migration of CO2 and the available pore space in the re...

Over 2.5 Mt CO 2 and 2.0 Mt H 2 S have been injected into deep saline aquifers and depleted hydrocarbon reservoirs at 48 sites in western Canada by the end of 2003, driven by the need to dispose of H 2 S produced with natural gas from sour gas reservoirs. Injection of acid gas (CO 2 and H 2 S) occurs over a wide range of aquifer and reservoir chara...

Acid-gas injection in the Alberta basin in western Canada occurs over a wide range of subsurface characteristics, acid gas compositions, and operating conditions. The subsurface characteristics of the injection sites are representative for compacted continental sedimentary basins, like those in the North American mid-continent. No safety or leakage...

Publisher Summary This chapter presents first methodology for evaluating the density and viscosity of native fluids and acid gas at in-situ conditions, and then applies this methodology to the case of acidgas injection operations in western Canada that cover a wide range of acid-gas composition, pressures and temperatures. The chapter implies algor...

Many deep saline aquifers suitable for CO2 injection are located in mature, onshore sedimentary basins of North America. These basins have been subjected to more than a century of oil and gas exploration and production, as well as the more recent practice of deep waste disposal. This legacy of drilling has resulted in large numbers of wells, a sign...

Sequestration in deep underground formations of large amounts of CO2, captured from large stationary sources, such as power plants, oil upgraders and refineries, is one method that is under consideration for reducing greenhouse gas emissions to the atmosphere in both Canada and United States. In hydrocarbon-producing regions, such as Texas in the U...

A key to the success of long-term storage of CO2 in depleted oil or gas reservoirs is the hydraulic integrity of both the geological formations that bound it, and the wellbores that penetrate it. This paper provides a review of the geomechanical factors affecting the hydraulic integrity of the bounding seals for a depleted oil or gas reservoir slat...

In many locations in North America, likely injection sites for CO 2 storage in deep geological formation are located in mature sedimentary basins. These basins have a century-long history of oil and gas exploration and production, which has led to hundreds of thousands of wells (the Alberta Basin) to more than a million wells (Texas) being drilled....

Oil and gas reservoirs and deep saline aquifers are primary candidates for long-term geological sequestration of greenhouse and acid gases. Risk assessment for sequestration projects must include predictions of sequestration zone performance. These performance assessments will guide the selection of sequestration sites and/or operating parameters,...

Injection of fluids into deep saline aquifers is practiced in several industrial activities, and is being considered as part of a possible mitigation strategy to reduce anthropogenic emissions of carbon dioxide into the atmosphere. Injection of CO2 into deep saline aquifers involves CO2 as a supercritical fluid that is less dense and less viscous t...

Capture and subsequent injection of carbon dioxide into deep geological formations is being considered as a means to reduce anthropogenic emissions of CO2 to the atmosphere. If such a strategy is to be successful, the injected CO2 must remain within the injection formation for long periods of time, at least several hundred years. Because mature con...

Injection of CO2 into deep saline aquifers in sedimentary basins appears to be an important means for reducing anthropogenic emissions of CO2 into the atmosphere. In the design, approval and monitoring of such operations it is important to predict the evolution of the plume of injected CO2 and identify potential leakage pathways. In mature sediment...

The authors have collected available data on more than 330 onshore candidate geological reservoirs in the United States and Canada, and have developed and employed a methodology for estimating the effective storage capacities of deep saline formations, depleted oil and gas reservoirs, and coal basins. Results indicate a large and variably distribut...

This chapter describes the underground injection of carbon dioxide in salt beds. Sequestration of CO2 in salt caverns allows significantly higher sequestration efficiency (by at least one order of magnitude) than geological sequestration of CO2 by other means. Although CO2 is not as hazardous as methane and other natural gases commonly stored in sa...

Geological storage of CO2 in mature sedimentary basins of North America requires special consideration of the large number of existing wells. Those wells represent potential leakage pathways for the stored CO2, and must be analyzed in the context of an overall environmental risk assessment. Analysis of well patterns in the Alberta basin, Canada, in...