The most common oil recovery method involves the injection of water into the oil reservoir to increase pressure and thereby stimulate oil production. This method is called the waterflood or water injection approach. In recent years however, the method of CO2 enhanced oil recovery has gained significant attention within the petroleum industry.
CO2 enhanced oil recovery involves the injection of CO2 into the reservoir. Unlike water flooding that limits recovery to 25-50% of the original oil being left behind, the CO2 method can recover a considerable part of residual trapped oil.
The Saudi Aramco project
Using kwik-ZIP centralizers, one of UTMN wells was drilled as an evaluation well by Saudi Aramco’s CO2 EOR pilot project. The project was conducted to provide additional source information and data control to monitor CO2 plume and migration within the pilot area.
The well was equipped with non-metallic casing and centralizers for electromagnetic monitoring (EM) and diffusion logging.
The non-metallic casing chosen for the project was Centron DHC 500 Series fibreglass with an outside diameter of 7.4’’.
Why were Kwik-ZIP spacers chosen?
Technical issues that arose during construction of the evaluation well lead the Aramco engineers to investigate the use of kwik-ZIP ® HD Series centralizers, via kwik-ZIP’s agent in Saudi Arabia, Energy Projects Support Company Ltd (ENPRO).
The client had planned to use zinc alloy non-magnetic rigid slip-on centralizers to centralise the casing, however, due to the unique diameter of the fibreglass casing, the rigid centralizers dimensions would result in unwanted movement.
Slight movement of the spacers could result in damage to the fibreglass so a different spacer was needed.
“The requirement of non-magnetic centralizers to be fitted with stop collars was also problematic, as the collar bolts could punch holes and cause cracks within the fibreglass,” said Kwik-ZIP’s Managing Director, Jason Linaker.
Following tests at an Aramco facility in Saudi Arabia, the kwik-ZIP HD 30 bow spring centralizer was approved for the project.
“Our products were chosen by Aramco as they have integrated rubber pads to prevent the movement on both steel and fibreglass casing, eliminating the need for stop collars,” Mr Linaker said.
“The design of our spacers protected the pipe casing, whilst still being a very strong and durable product.
“Our centralizers have been developed by drilling professionals and include elements such as rubber pads, one of the innovations we saw lacking in other products within the spacing and centralizer market.”
The outer diameter (OD) of the fibreglass pin and box upsets of the Saudi Aramco project’s casing would also not suit the OD of the rigid zinc alloy slip-on centralizers.
“Rigid slip-on centralizers would not have provided the required standing forces in the hole,” Mr Linkaker said.
“The curved bow profile and low friction coefficient of kwik-ZIP centralizers however, enabled the centralizer to be compressed, passed through the outer casing and expanded back to the diameter of the larger hole.”
Mr Linaker said the kwik-ZIP products provided the required standing forces in the hole for better cementing distribution. This has been verified by the client, who reported that, “Aramco have run the liner into the well without any issues and the cement bond log (CBL) has been completed, verifying a very good cement bond”.
“It is the flexibility and versatility of kwik-ZIP products that make them so attractive to clients and contractors, as the same centralizers can be used across a range of pipe specifications within the one installation,” said Mr Linaker.
“As kwik-ZIP centralizers are made from high grade thermoplastic, they are well suited to projects that require non-metallic or inert equipment.
“In the case of the Saudi Aramco project, the plastic centralizers along with the fibreglass casing would not interfere with the electromagnetic monitoring process.”