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Posted Content•DOI•

Innovative CO 2 Injections in Carbonates and Advanced Modelling for Numerical Investigation

de Dios Jc, Le Gallo Y, Marín Ja
27 Jul 2018-
TL;DR: In this article, the behavior of fractures in carbonates plays a key role in those reservoirs in which porous matrix permeability is very poor, which drives the CO2 plume migration through the fracture network where hydromechanics and geochemical effects take place due to injection.
Abstract: CO2 geological storage in deep saline aquifers was recently developed at industrial scale mainly in sandstone formations. Experiences on CO2 injections in carbonates aquifers for permanent trapping are quite limited, mostly from US projects such as AEP Mountaineer, Michigan and Williston Basin. The behavior of fractures in carbonates plays a key role in those reservoirs in which porous matrix permeability is very poor, which drives the CO2 plume migration through the fracture network where hydromechanics and geochemical effects take place due to injection. Hontomín (Spain) is the actual on-shore injection pilot in Europe (EP Resolution of 14 January 2014), whose reservoir is comprised of fractured carbonates. Existing experiences from field scale tests conducted on site have supported to better understand the behavior of this type of reservoirs for CO2 geological storage. Innovative CO2 injection strategies are being carried out in ENOS Project (EU H2020 Programme, http://www.enos-project.eu). First results based on field tests conducted at Hontomín, and the advanced modelling developed so far will be analyzed and discussed in this article, as well as, the description of future works. The evolution of operating parameters such as flow rate, pressure and recovery term during the tests confirm the CO2 migration through the fractures.

Summary (1 min read)

Jump to: [Introduction] and [7 CONCLUSIONS]

Introduction

  • Hontomín is the actual on-shore injection pilot in Europe (EP Resolution of 14 January 2014), whose reservoir is comprised of fractured carbonates.
  • The design of safe CO2 injection strategies and the understanding of trapping mechanisms in carbonates with poor matrix porosity and fluid transmissivity through the fractures are challenging matters so far.
  • Initial and final values of referred parameters during CO2 injection are shown in table 1. BHP in HA well remains constant along the test what proves there is not fluid transmissivity through the seal.
  • The modelling followed a sequential approach: first matching the single phase parameters such as fracture permeability during the brine injection periods and then matching the two-phase parameters such as fracture relative permeability during the brine and CO2 injection periods.

7 CONCLUSIONS

  • Results from first injection tests conducted at Hontomín site within ENOS project confirmed the singularity of this reservoir where CO2 migration is through the carbonate fractures.
  • On the other hand, when flow value is constant during injection the well head pressure highly increases as much CO2 is injected on site.
  • As regards the period of time necessary for pressure recovery on the bottom hole during the fall-off phase, it depends on the injected fluid due to different hydraulic properties, and the cumulative amount of CO2 existing on site.
  • Regarding the thermal profiles corresponding to injections, liquid CO2 phase is ensured along the tubing which corresponds with an efficient operation, reaching fluid density values close to 0,83 t/m3 at the bottom hole.

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1
Innovative CO
2
injections in carbonates and advanced modelling for
numerical investigation
J.Carlos de Dios
a*
, Yann Le Gallo
b
, Juan A. Marín
a
a
Foundation Ciudad de la Energía (CIUDEN). Avenida del Presidente Rodríguez Zapatero 24492
Cubillos del Sil (Spain)
b
Geogreen, 2 Rue des Martinets 92500 Rueil-Malmaison (France)
Corresponding author
#
: jc.dedios@ciuden.es
e-mail address authors: ylg@geogreen.fr ; ja.marin@ciuden.es
1. ABSTRACT
CO
2
geological storage in deep saline aquifers was recently developed at industrial scale mainly
in sandstone formations. Experiences on CO
2
injections in carbonates aquifers for permanent
trapping are quite limited, mostly from US projects such as AEP Mountaineer, Michigan and
Williston Basin.
The behavior of fractures in carbonates plays a key role in those reservoirs in which porous
matrix permeability is very poor, which drives the CO
2
plume migration through the fracture
network where hydromechanics and geochemical effects take place due to injection.
Hontomín (Spain) is the actual on-shore injection pilot in Europe (EP Resolution of 14 January
2014), whose reservoir is comprised of fractured carbonates. Existing experiences from field
scale tests conducted on site have supported to better understand the behavior of this type of
reservoirs for CO
2
geological storage.
Innovative CO
2
injection strategies are being carried out in ENOS Project (EU H2020 Programme,
http://www.enos-project.eu). First results based on field tests conducted at Hontomín, and the
advanced modelling developed so far will be analyzed and discussed in this article, as well as,
the description of future works. The evolution of operating parameters such as flow rate,
pressure and recovery term during the tests confirm the CO
2
migration through the fractures.
Keywords: CO
2
Storage, carbonate fractures, ENOS, operating parameters, advanced modelling
Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 27 July 2018 doi:10.20944/preprints201807.0537.v1
© 2018 by the author(s). Distributed under a Creative Commons CC BY license.
2
2. INTRODUCTION
Most of experiences on CO
2
geological storage worldwide have been conducted in rock
formations with high permeability in the pore matrix, mainly in sandstones [Michael et al.,
2011] [Krevor et al., 2012] [Torp and Gale 2004] and in some cases in carbonates such as
AEP Mountaineer Project [Gupta 2008] [Mishra et al., 2013], Michigan and Williston Basin
[Finley et al., 2013] [Worth et al., 2014] in USA. There are also CO
2
-EOR projects which injects
CO
2
in carbonate formations such as the IEAGHG Weyburn-Midale CO
2
project [Wilson and
Monea, 2004] in Canada and the Uthmaniyah CO
2
-EOR demonstration project in Saudi
Arabia [Liu et al., 2012]
The design of safe CO
2
injection strategies and the understanding of trapping mechanisms
in carbonates with poor matrix porosity and fluid transmissivity through the fractures are
challenging matters so far. To give a proper solution, the study of hydrodynamic and
mechanical effects induced by the CO
2
plume migration in the fractures, and those ones
produced by the geochemical reactivity due to the acidification of reservoir water, is needed
to increase the knowledge on the behavior of these reservoirs for CO
2
geological storage
and later industrial deployment [de Dios et al., 2017].
Hontomín Pilot Plant [Neele et al., 2014], operated by Fundación Ciudad de la Energía
(CIUDEN), is the only current onshore injection site in Europe for CO
2
geological storage,
recognized by the European Parliament [EP resolution 2014] as key test facility for CCS
technology development. The pilot is located close to Burgos in the north of Spain, and its
reservoir is comprised of fractured carbonates with poor matrix porosity [Campos et al.,
2014].
To demonstrate innovative injection strategies and history matching approaches for
increased confidence of operators in safely managing sites is a priority within ENOS Project
(EU H2020 Programme, http://www.enos-project.eu). It is expected to increase the
understanding on CO
2
injection in fractured carbonates with low primary permeability, and
to develop safe and efficient operational procedures using real-life experience from running
the Hontomin pilot [Gastine et al., 2017].
CO
2
injection in rock formations with main fluid transmissivity through fractures usually
requires high values of pressure, which means a risk for the pair seal-reservoir integrity
[Vilarasa et al., 2014]. On the other hand, as mentioned above, the geochemical reactivity
due to reservoir water acidification impacts on the carbonate permeability [Gaus et al.,
2015]. These matters must be considered to design safe and efficient injection strategies in
ENOS project to improve the hydrodynamic stability and control of storage integrity. First
injections conducted at Hontomín using synthetic brine and CO
2
will be described in the
article, analyzing the evolution of operational parameters and discussing the results.
To model the CO
2
migration through the fractures and predict the injection effects in the
carbonates is a challenge as well. An advanced modeling workflow with FracaFlow™ used to
elaborate a Digital Fracture Network (DFN) [Bourbiaux et al., 2005] around the injection well
and characterize the main properties of the fracture network will be described in the article.
The dynamic characterization of fracture properties was then performed using an advanced
automated history matching with CMOST™ to model the pressure behavior around the
injection well based upon a previous modelling work [Le Gallo et al., 2017].
Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 27 July 2018 doi:10.20944/preprints201807.0537.v1
3
Taking into account the first results from injections and the modelling developed so far, the
authors will describe the planned works to be conducted in ENOS project in order to find
solutions based on real life experiences.
The results from first injections performed at Hontomín site confirmed the singularity of this
reservoir where CO
2
migration is through the carbonate fractures. The evolution of main
operational parameters such as well head pressure (WHP), flow rate, bottom-hole pressure
(BHP) and distributed temperature along the well tubing confirm the injection of CO
2
in
liquid phase. Taking into account the information provided by the first results, it is necessary
to determine the long term evolution of BHP and flow regarding the injection strategy used
and particularly the pressure recovery period during the fall-off phase according to the
cumulative amount of CO
2
injected on site.
3. DESCRIPTION OF PILOT PLANT
Hontomín site represents a structural dome where the pair seal-reservoir is located within
Jurassic Formations (Marly Lias and Sopeña respectively). Overburden is formed of Dogger,
Purbeck and Weald and the underlying seal is located at Triassic Keuper [Rubio et al., 2014].
Figure 1 shows the lithological column of Hontomín site and the geological cartography of
the area.
Fig 1.- Lithological column and geological map of Hontomín area
Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 27 July 2018 doi:10.20944/preprints201807.0537.v1
4
Pair seal-reservoir is located at the depth of 900 in the top of the dome and 1832 m in flanks.
Marly Lias and Pozazal form the main seal (160 m thick) comprised of marls, shales, limestones
and calcareous mud stones. Carbonates reach the average of 50% in the seal composition.
Reservoir is Sopeña Formation (120 m thick) comprised of limestone at its upper part and
dolomites at the bottom [Kovacs 2014], with a high level of fracturing in different geological
blocks which does not affect the seal integrity.
Two wells were specifically drilled and monitored during the site construction reaching the
depth of 1600 m, one for injection (HI) and other for observation (HA) [de Dios et al., 2016]. HI
well is equipped with super duplex tubing anchored to the liner by a hydraulic packer (1433 m
MD), two P/T sensors below, Distributed Temperature Sensing System (DTS) and Distributed
Acoustic Sensing System (DAS) along the tubing, six ERT electrodes and a deep water sampling
(U tube) installed in the bottom hole.
On the other hand, HA well is equipped with a fiber glass tubing anchored to the liner with 3
inflatable packers (1275 m, 1379 m and 1497 m MD) which distribute the open hole in intervals
with different permeability, 4 pressure/temperature (P/T) sensors and 28 ERT electrodes
installed in the seal and reservoir. Both well schemes are shown in figure 2.
Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 27 July 2018 doi:10.20944/preprints201807.0537.v1
5
Fig 2.-Schemes of injection well HI (left side) observation well HA (right side) and panoramic
view of the pilot
Facilities for CO
2
injection and water conditioning, the seismicity monitoring network comprised
of 30 passive seismic stations covering an area of 18 Km
2
and hydrogeological monitoring wells
to control shallow aquifers also form part of the pilot.
The main challenge faced during Hontomín hydraulic characterization was the low injectivity
existing on site. The injection of brine and CO
2
to characterize the pair seal-reservoir produced
geomechanical changes and geochemical reactivity effects that improved the permeability in
the fracture network while the matrix does not appear to significantly contribute to the storage
capacity for the time being [de Dios et al., 2017].
Hontomín is at the early injection phase, thus, all long term effects that condition the safe and
efficient CO
2
geological storage must be determined and analyzed.
4. INNOVATIVE CO
2
INJECTION STRATEGIES
It is planned to inject on site up to 10 000 metric tonnes of CO
2
during the period 2016-2020 in
ENOS project, with the purpose of better knowing the behavior of this tight fractured reservoir,
mainly what concerns the improvement of hydrodynamic stability and control of storage
integrity, for finding safe and efficient operation conditions.
Therefore, the design of CO
2
injection strategies to be conducted in the project must be based
on criteria of efficiency and safety, for later up-scaling to industrial deployment. The operating
procedures must ensure efficient energy consumption, maximizing reservoir capacity and
preserving seal integrity [Gale et al., 2001].
As mentioned before, CO
2
injection in carbonate reservoirs with low matrix permeability shows
specific features that are different from injection in porous media. Considering the CO
2
migration
is dominated by the fracture network, the following gaps need to be studied in order to define
proper strategies for the injection:
• Bottom-hole pressure (BHP) evolution and its influence in the cap-rock integrity and
reservoir behavior
• Bottom-hole temperature (BHT) evolution and the analysis of thermal effects due to
injection
• Monitoring CO
2
evolution along the well tubing and the fluid density reached at the
bottom hole.
• Energy consumption and operation performance for each planned injection
Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 27 July 2018 doi:10.20944/preprints201807.0537.v1
Citations
More filters
Journal Article•DOI•
Geological Model of a Storage Complex for a CO2 Storage Operation in a Naturally-Fractured Carbonate Formation

[...]

Yann Le Gallo, José Carlos de Dios
19 Sep 2018
TL;DR: In this article, a geological model encompassing the whole storage complex was established based upon newly-drilled and legacy wells and the matrix characteristics were mainly obtained from the newly drilled wells with a complete suite of log acquisitions, laboratory works and hydraulic tests.
Abstract: Investigation into geological storage of CO2 is underway at Hontomin (Spain). The storage reservoir is a deep saline aquifer formed by naturally fractured carbonates with low matrix permeability. Understanding the processes that are involved in CO2 migration within these formations is key to ensure safe operation and reliable plume prediction. A geological model encompassing the whole storage complex was established based upon newly-drilled and legacy wells. The matrix characteristics were mainly obtained from the newly drilled wells with a complete suite of log acquisitions, laboratory works and hydraulic tests. The model major improvement is the integration of the natural fractures. Following a methodology that was developed for naturally fractured hydrocarbon reservoirs, the advanced characterization workflow identified the main sets of fractures and their main characteristics, such as apertures, orientations, and dips. Two main sets of fracture are identified based upon their mean orientation: North-South and East-West with different fracture density for each the facies. The flow capacity of the fracture sets are calibrated on interpreted injection tests by matching their permeability and aperture at the Discrete Fracture Network scale and are subsequently upscaled to the geological model scale. A key new feature of the model is estimated permeability anisotropy induced by the fracture sets.

13 citations

Cites methods from "Innovative CO 2 Injections in Carbo..."

  • ...As the approaches to elaborate and calibrate the DFN are statistically based, the results presented in this paper shall only be considered as initial and it will serve as the basis to the future full-field history matching of the CO2 and brine injection tests which will be performed within the ENOS project [33]....

    [...]

Journal Article•DOI•
Effect of scCO2-brine mixture on injectivity and storage capacity in rock samples of naturally fractured carbonate formations

[...]

L.M. Valle1, C. Grima1, R. Rodríguez1, C. Llopis2•
Technical University of Madrid1, Polytechnic University of Valencia2
01 Sep 2020-Journal of Natural Gas Science and Engineering
TL;DR: In this paper, the petrophysical behavior of two carbonate formations was studied, with different proportions of limestone, dolomite, quartz and anhydrite and fissures sealed mainly by potassium aluminosilicates and iron sulphides.
Abstract: The presence of natural fractures in the formation and its degree of heterogeneity condition the injection of CO2 into the aquifer as they affect the migration processes and its storage capacity In ATAP experimental facility the petrophysical behavior of two carbonate formations was studied, with different proportions of limestone, dolomite, quartz and anhydrite and fissures sealed mainly by potassium aluminosilicates and iron sulphides Actual storage conditions (135/141 bar and 44/46 ᵒC) corresponding to a depth of around 1500 m and continuous injection at a constant flow rate of 1 cc/min of 10% and 15% of HCl, HCl/Acetic (CH3COOH) 10%/10% and scCO2 (supercritical CO2)/brine 50%/50%, was applied to the brine saturated rock samples (coreflooding) Considering laminar flow through the fractures, the flow injected is proportional to the pressure drop according to the “cubic law” that takes into account the width and length of the fractures This is used to evaluate the injectivity of the storage The variations in the pressure drop are due to the dragging of detached fines in the dissolution of the carbonates of the filled fissures that can cause their opening or blocking The efficacy of pure scCO2 enriched brine injection was determined to dissolve the carbonates of the store formation compared to other methods such as the injection of acids used in the oil industry for the stimulation of producing wells Scanning Electron Microscope (SEM) studies of the injection surfaces and Computerized Tomography (CT) analysis of the samples before and after injection of the acid mixtures have been performed The dissolution facilitates the injectivity and increases the capacity favoring the tightness of the storage by the phenomenon of controlled dissolution-precipitation of the carbonates

8 citations

Posted Content•DOI•
Characterizing a Naturally-Fractured Carbonate Formation for a CO2 Storage Operation

[...]

Yann Le Gallo, José Carlos de Dios
23 May 2018
TL;DR: In this paper, the authors used a compositional dual media model to simulate the injection of CO2 and synthetic brine at the Technology Development Plant (TDP) at Hontomín (Burgos, Spain).
Abstract: Investigation into geological storage of CO2 is underway at the Technology Development Plant (TDP) at Hontomín (Burgos, Spain), the only current onshore injection site in the European Union. The storage reservoir is a deep saline aquifer located within Low Jurassic Formations (Lias and Dogger), formed by fractured carbonates with low matrix permeability. Understanding the processes involved in CO2 migration within this kind of low-primary permeability carbonates influenced by fractures and faults is key to ensure safe operation and reliable plume prediction. During the hydraulic characterization tests, 2300 tons of liquid CO2 and 14000 m of synthetic brine were co-injected on site in various sequences to characterize the pressure response of the seal-storage pair [de Dios et al, 2017] The injection tests were analyzed with a compositional dual media model which accounts for both temperature effects (as the CO2 is liquid at the bottom of the wellbore) and multiphase flow hysteresis (to effectively simulate the alternating brine and CO2 injection tests that were performed). The pressure and temperature responses of the storage formation were historymatched mainly through the petrophysical characteristics of the fracture network [Le Gallo et al, 2017]. The dynamic characterization of the fracture network dominates the CO2 migration while the matrix does not appear to significantly contribute to the storage capacity. This initial modeling approach was improved using the characterization workflow developed within the European FP7 CO2ReMove project for sandstone fractured reservoirs [Ringrose et al., 2011; Deflandre et al., 2011]. Fractured reservoirs are challenging to handle because of their high level of heterogeneity that conditions the reservoir behaviour during the injection. In particular, natural fractures have a significant impact on well performance [Ray et al, 2012]. Furthermore, the understanding of the processes involved in CO2 migration within relatively low-permeability storage influenced by fractures and faults is essential for enabling safe storage operation [Iding and Ringrose, 2010]. As part of the European H2020 ENOS project, the site geological model is updated by integration of the recently acquired data such as the image log interpretations from injection and observation wells. The geological model is generated through the analysis and integration of data including borehole images and well test data. Following a methodology developed for naturally fractured hydrocarbon reservoirs [Ray et al., 2012], the image log analysis identified two sets of diffuse fractures. A Discrete Fracture Network [Bourbiaux et al., 2005] was built around both wells which encompass the caprock, storage and underburden formations. The fracture characteristics of the two sets of diffuse fractures, such as orientations, densities and conductivities, are calibrated upon the interpretation of the injection tests [Le Gallo et al, 2017]. For each facies, the DFN characteristics were then upscaled and propagated to the full-field reservoir simulation model as 3D fracture properties (fracture porosity, fracture permeability and equivalent block size). Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 23 May 2018 doi:10.20944/preprints201805.0324.v1 © 2018 by the author(s). Distributed under a Creative Commons CC BY license. Peer-reviewed version available at Geosciences 2018, 8, 354; doi:10.3390/geosciences8090354

1 citations

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TL;DR: The Sleipner project is the first commercial application of CO2 storage in deep saline aquifers in the world as discussed by the authors, and 3D seismic surveying has been used to successfully monitor the CO2 in the Utsira formation.
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Abstract: The member countries of the European Union plan to reduce their CO2 emissions in accordance with the international protocol agreed in Kyoto in 1997. The accepted options for doing this include fuel switching, improving energy efficiency, and the introduction of renewable energy sources. Geological storage of CO2 from fossil fuel use is also an option to reduce CO2 emissions, which does not require major changes in the energy infrastructure. Two projects are now under way in the European Union to study the potential for geological CO2 storage. The first project, known as GESTCO, will assess the potential CO2 storage capacity of the main sedimentary basins within Europe. GESTCO will examine in detail the geological storage potential and coincidence of CO2 emission sources to storage sites. In the North Sea the world’s first commercial geological storage project has now been in operation for 3 years. The natural gas from the Sleipner West field contains about 9% CO2, which must be reduced to 2.5% before sale. The CO2 is stripped by an amine scrubbing plant and then injected into a deep saline reservoir about 800 m below the seabed. To date, about 3 million tonnes of CO2 have been injected. To monitor the storage of CO2 in the reservoir, a project entitled Saline Aquifer CO2 Storage commenced in April 1998.

82 citations

Frequently Asked Questions (2)
Q1. What are the contributions in "Innovative co2 injections in carbonates and advanced modelling for numerical investigation" ?

First results based on field tests conducted at Hontomín, and the advanced modelling developed so far will be analyzed and discussed in this article, as well as, the description of future works. 

The future modelling work shall focus upon the pressure fall-off periods which appears faster in the model than in the field.