First Application of a Novel Self-Healing and CO2-Resistant Cement on a Deepwater Cementing Operation
Authors: Azwar Cinto , Kusumawatie Reny , Osman Ahmed , Jain Bipin , Wedhaswari Victoria Rasmi , Simanjuntak Andre , Afrianto Agung Arya , Siregar Y. Ronny Costamte , Firnanto Andrean 
Published: March 2023

Harbour Energy began offshore exploration in the Andaman Sea in North Sumatra, Indonesia with the Timpan-1 well. During the planning phase, reservoir sections of the well were identified that contained circa 5-15% of CO2 levels as per the offset well data, which are corrosive environments and can cause cement sheath degradation. This paper presents the decision process used in selecting a suitable system for the CO2-rich environment and the first-time application of pumping novel self-healing and CO2-resistant cementing system with its capability to self-heal upon contact with CO2.

Conventional Portland cement degrades in CO2-corrosive environments and combined with cement sheath damage by downhole stresses, long-term well integrity will be compromised. The auto repair capabilities provided by the novel cement system when in contact with CO2 leaking-fluids ensure long-term well integrity. Although self-healing-to-hydrocarbons cements have been widely used in the industry, use of this newly developed novel self-healing CO2-resistant cement was implemented for the first time in a primary casing job. To ensure blend consistency of the novel self-healing CO2-resistant cement, a number of quality control processes were developed with extensive laboratory testing and implemented for the complete blend lifecycle management.

Implementation of this novel self-healing CO2-resistant cement in a deep-water primary casing job requires validation of crucial factors meet the requirements of achieving the long term well integrity. During the preparation phase, this cementing system was exposed to a high-CO2 corrosive environment over an extended period to analyze the robustness. The results showed superior properties compared with a conventional Portland system. The self-healing properties, analyzed with the use of an actual crack in the set cement and observed to the point where the crack closed, demonstrated continued cement integrity. Slurry stability tests produced excellent results. Blend flowability and robustness tests were performed at a regional laboratory using specialized equipment and determined the blend to be suitable for offshore operations. In implementation phase, by adhering to the project management process developed, the primary casing cement job was successfully performed without incident using conventional cementing equipment and practices. Good cement bond was obtained across the main zone, and the rig was able to continue its operations to perforate and well test the well.

The 2001 Greenhouse Gas (GHG) Protocol's guidelines categorized business GHGs as scope 1 emissions, scope 2 emissions, and scope 3 emissions. The aim of this emission classification system was to help organizations measure and manage their carbon footprint (www.greenbusinessbureau.com 2022). Scope 1 emissions are GHGs released directly from a business. Scope 2 emissions are indirect GHGs released from the energy purchased by an organization. Scope 3 emissions are also indirect GHG emissions, accounting for upstream and downstream emissions from a product or service, and emissions across a business's supply chain. The novel self-healing CO2-resistant cement produces 63% less CO2 compared with a conventional Portland cement system. Implementing the novel slurry system will significantly reduce Scope 3 of CO2 emission that is embedded during the manufacturing of the materials used. In addition to that, due to its self-healing capability, the novel CO2-resistant cement will contribute on Scope 1 CO2 emission reduction by eliminating the need to perform remedial work in case of a well leak. The solution meets the long-term well integrity requirement and is in line with the global commitment to reduce the carbon emission footprint.