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Shell Chemicals offers a range of ENORDET surfactants for enhanced oil recovery. These products are being used in pilots around the world to demonstrate the potential of surfactant-based technologies to recover more oil from existing reservoirs.
Shell Chemicals is building on long-standing experience in surfactant manufacturing to develop and manufacture high performing enhanced oil recovery surfactants.
What is enhanced oil recovery?
Enhanced oil recovery (EOR) is a term that describes a group of technologies designed to increase the recovery of oil from oil reservoirs. When an oil field reaches the end of its normal life, as much as two-thirds of the oil can be left in the ground because it is too difficult or too expensive to get out. By recovering just 1% of that extra oil, it is estimated that the equivalent of 88 billion barrels of oil would become available.
One of the EOR technologies is Alkaline Surfactant Polymer flooding or ASP-flooding. The ASP ingredients are dissolved in water and used to flood the oil reservoir. Shell Chemicals supplies surfactants used in this technology.
What are ENORDET surfactants for enhanced oil recovery?
ENORDET is short for ENhanced Oil Recovery DETergents. These materials are surfactants, based on alcohol alkoxy sulfates (alkyl ether sulfates) and internal olefin sulphonates.
Shell Chemicals is building on long-standing experience in surfactant manufacturing to develop and manufacture high-performing EOR surfactants.
How are ENORDET surfactants used?
The oil reservoir is first flooded by adding water containing a small percentage of surfactant. Surfactants can lower the crude oil/water interfacial tension (IFT) to an ultra-low level allowing oil globules in the reservoir to flow through rock pores and coalesce to form a clean bank of oil. To make this work, specific surfactants need to be selected and matched to specific reservoir conditions, taking into account:
- Water salinity and divalent ion (Ca, Mg) concentration
- Crude oil type (total acid number, viscosity, etc)
Selection of the right surfactant is important in preventing the formation of higher viscosity emulsions, which would otherwise become trapped and prevent effective transport of the surfactant solution through the reservoir.
Alkali, usually in the form of sodium carbonate (soda-ash), is often added to the aqueous solution to increase efficiency. It generates natural soaps through reaction with acids in the crude oil and also reduces surfactant absorption on rock surfaces. A water-soluble polymer is usually added to increase the viscosity of the water phase.
The ASP solution is usually followed by a polymer solution that acts as a piston to push the oil through the reservoir to the producing wells.
What are our key strengths as a supplier of enhanced oil recovery surfactants?
Supply security: Shell is the largest integrated producer of internal olefins, alcohols and ethoxylates globally. Our manufacturing processes, which are ISO 9001 and ISO 14001 certified, have proven themselves over decades.
Proven technology: the Shell Higher Olefin Process (SHOP) underpins the manufacture of cost effective high molecular weight internal olefin sulfonates. The Shell Hydro Formylation (SHF) process offers unique alcohol manufacturing flexibility.
Technical support: our technical specialists, located in Houston and Amsterdam, work closely with customers to identify the appropriate products for their needs, and to optimise customer formulations. See also ‘Customer formulation support'.
Flexible solutions: by making a crude-specific formulation, comprising two or three ENORDET surfactants, a wide range of crude oils and reservoir conditions can be matched.
Currently, we offer two main product lines: the alcohol alkoxy sulfates (AAS) and the internal olefin sulphonates (IOS). Blending these different surfactants in various ratios allows the Alkaline Surfactant Polymer solution to be matched to the reservoir conditions, so achieving optimal EOR performance.
The benefits of each surfactant type can be summarised as follows:
For both groups, the molecular structure has been tailored to work at different reservoir salinities and with different crude oil types. Combinations of ENORDET surfactants work in complementary ways Choosing the correct combination will help to prevent the formation of high micro-emulsion viscosities and gel-phases, which may otherwise hamper efficient transport of oil through the reservoir pores.
Sometimes, the use of a co-solvent (such as IBA or SBA) in combination with ENORDET surfactants can help in reducing micro-emulsion viscosities and so improve the sweep efficiency and oil recovery
Concentrated ENORDET surfactants
Key data for popular ENORDET surfactants
||Surfactant type||C20-24||Applicable salinity||PO/EO per alcohol unit (mol/mol)||Applicable temperature range||Di-valent ion tolerance|
|O242||IOS||C20-24||low/med||N/A||ambient to 200°C||limited|
||high||N/A||ambient to 200°C||limited|
|O342||IOS||C19-23||medium||N/A||ambient to 200°C||limited|
|O352||IOS||C24-28||low||N/A||ambient to 200°C||limited|
|A771||AAS||C16-17||low/med||7 PO||ambient to ≥ 60°C||excellent|
|A031||AAS||C16-17||med/high||3 EO||ambient to ≥ 60°C||excellent|
|J771||AAS||C12-13||low/med||7 PO||ambient to ≥ 60°C||excellent|
|J11111||AAS||C12-13||low/med||11 PO||ambient to ≥ 60°C||excellent|
|J13131||AAS||C12-13||low/med||13 PO||ambient to ≥ 60°C||excellent|
|J071||AAS||C12-13||very high||7 EO||ambient to ≥ 60°C||excellent|
- IOS: internal olefin sulfonate
- AAS: alcohol alkoxy sulfate, or alkyl ether sulfate
- Applicable salinity: the range of salinities where a surfactant can be applied is formulation dependent
- Applicable temperature range: for the AAS, up to 60°C for SP formulations, slightly higher for ASP formulations
- Di-valent tolerance: effective di-valent ion tolerance is formulation dependent
Sometimes, it is preferable to ship concentrated surfactants, minimising transport costs and reducing storage space. Depending on the concentration and surfactant type, the ENORDET surfactants can range in physical properties from low viscosity liquids to higher viscosity pastes.
To simplify operations in the field, it may be better to ship the surfactant system as a concentrated blend rather than ship the single surfactants. This has the advantage of only needing one surfactant storage tank and there is no need for surfactant mixing on-site. An additional benefit is that a combination of IOS and AAS surfactants often results in a lower viscosity liquid, which is easier to handle than a paste.
We can support our customers in developing their formulations. Using our expertise, we can help to develop a surfactant combination that results in an ultra-low interfacial tension (IFT) with the crude, which is essential for good oil recovery.
Crude-oil parameters, like total acid number (TAN) and viscosity, may be taken into account when formulating, as well as brine composition - salinity and presence of di-valent ions such as Ca and Mg. The specific reservoir conditions, such as temperature, permeability and rock type, as well as practical considerations such as the availability of fresh water or softened (saline) water, will also need to be discussed. Flood performance testing, using the customer’s crude-oil and brine under the prevailing reservoir conditions, can be offered.
Additional practical considerations to include are the constraints posed by the location. For example, off-shore locations often have lmited storage space, weight and power.
Concentrated ENORDET surfactant blends
To simplify operations in the field, it may be preferable to ship the surfactant system as a concentrated blend rather than ship the single surfactants.
In these circumstamces, Shell Chemicals can develop a customer-specific, concentrated blend. The parameters to be taken into account will be discussed with the customer. These can include prevailing climate, storage options, logistic challenges (eg off-shore supply), modes of shipment, product unloading and mixing in the water stream. Given the many possibilities, blend development will need to be done in close collaboration with the customer.
Shell chemicals companies are large volume suppliers of surfactants and surfactant feedstock to major detergent manufacturers. We operate world class production facilities in Geismar, Louisiana (USA) and in Stanlow (UK), that are ISO 9001 and ISO 14001 certified. By being fully integrated with the ethylene feedstock supply chain, we offer a strong record of reliable supply to our customers.
We serve customers globally; products can be shipped using marine vessels, barges, railroad and trucks. Smaller quantities can be arranged in IBC or drums for small-scale pilot testing.
We work continually to reduce transport costs for our customers by offering more shipping options. Examples of our innovative approach include: high active matter (HAM) liquids and pastes, even more concentrated surfactant powders, and effective means to dilute these concentrates down to the required concentration of 0.3 – 1.0% in the final ASP solution.
Health, Safety, Security & Environment (HSSE)
Shell chemicals companies are committed to complying with all regulations during manufacture, transport, storage and use of our ENORDET surfactant products. HSSE specialists are available to support our customers in meeting their HSSE requirements.
- Application of Internal Olefin Sulfonates and Other Surfactants to EOR - Part 1: Industrial Production, Structure Performance Relationships, Handleability
Presented by Julian Barnes, Principal Researcher Higher Olefins and Derivatives/Chemical Enhanced Oil Recovery, Shell Global Solutions International
- Application of Internal Olefin Sulfonates and Other Surfactants to EOR - Part 2: The Design and Execution of an ASP Field Test
Presented by Marten Buijse, Principal Research Chemist for Enhanced Oil Recovery, Shell Global Solutions International
- Alkaline-surfactant-polymer flooding - Laboratory and single well chemical tracer test (SWCT) results
Presented by Rien Faber, Principal Research Chemist for Enhanced Oil Recovery, Shell Global Solutions International
Shell Chemicals presentations
- A variety of dovuments are available on the Society of Petroleum Engineers (SPE) website, access to this website being via subsctription.
|SPE number||Title||Date||Published by|
|SPE-159620||A New Approach to Deliver Highly Concentrated Surfactants for Chemical Enhanced Oil Recovery. Presented at the SPE Annual Technical Conference and Exhibition held in San Antonio, Texas, USA||8-10 October 2012||Shell|
|SPE-154084||Controlled Hydrophobe Branching to Match Surfactant to Crude Oil Composition for Chemical EOR. Presented at the 2012 SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||14-18 April 2012||Shell|
|SPE-129769-PP||Application of Internal Olefin Sulfonates and Other Surfactants to EOR. Part 2: The Design and Execution of an ASP Field Test". Presented at the 2010 SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||24–28 April 2010||Shell|
|SPE-129766-PP||Application of Internal Olefin Sulfonates and Other Surfactants to EOR. Part 1: Structure - Performance Relationships for Selection at Different Reservoir Conditions. Presented at the 2010 SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||24–28 April 2010||Shell|
|SPE-129675-PP||Surfactant systems for EOR for high salinity, high temperature environments. Presented at the 2010 SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||24–28 April 2010||Rice University and Shell|
|SPE-113314-PP||Phase Behaviour Methods for the Evaluation of Surfactants for Chemical Flooding at Higher Temperature Reservoir Conditions. Presented at the SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||19–23 April 2008||Shell and Rice University|
|SPE-113313-PP||Development of Surfactants for Chemical Flooding at Difficult Reservoir Conditions. Presented at the SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||19–23 April 2008||Shell and Rice University|
|SPE-100089||Identification and Evaluation of High Performance EOR Surfactants. Presented at the 2006 SPE/DOE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA||22-26 April 2006||University of Texas|