Development of Environmentally Friendly Metakaolin-Based Geopolymers for Oil Well Cementing and Well Abandonment - MGeo

Alle petroleumsbrønner blir permanent plugget og forlatt mot slutten av sin livssyklus når de ikke lenger er økonomisk levedyktige. Ordinary Portland Cement (OPC) er hovedmaterialet som i dag brukes som brønnsement ved plugging og forlating av brønner, og både i Norge og Brasil er det tusenvis av brønner som skal plugges i løpet de neste tiårene. Dette representerer et betydelig klimagassutslipp, ettersom produksjon av Portland sement slipper ut store mengder CO2. Det er derfor behov for å utvikle og teste alternative pluggematerialer med lavere CO2-fotavtrykk. I dette prosjektet samarbeider Cemonite (tidligere Saferock) med Universitetet i Stavanger og de brasilianske partnerne TECCIM Ltda og Universidade Federal do Rio Grande do Norte, om å utvikle og teste en metakaolin-basert geopolymer brønnsement. Geopolymerer, også kalt alkali-aktiverte materialer, er en type miljøvennlig bindemiddel uten Portland sement og som derfor har et betydelig lavere CO2-fotavtrykk enn tradisjonell brønnsement. Utgangsmaterialet metakaolin som brukes i prosjektet blir utvinnet i et brasiliansk dagbrudd. Prosjektet fokuserer på å forstå reaksjonsmekanismene under herdeprosessen, og bruk av ulike tilsetningsstoffer, slik at styrkeoppbygging, reologi og pumpbarhet kan kontrolleres. Resultatene viser at metakaolin-basert geopolymer brønnsement kan ha et potensiale som alternativt pluggemateriale.

In this project, Cemonite (former Saferock) collaborates with University of Stavanger and the Brazilian partners TECCIM Ltda and Universidade Federal do Rio Grande do Norte (UFRN), to develop and test a metakaolin-based geopolymer well cement. Portland Cement is commonly used today as well cementing and plugging material during well operations, which represents a significant CO2-footprint since Porland cement production is a major cause of CO2 emissions. Geopolymers on the other hand, also called alkali-activated materials, is a type of environmentally friendly binder without Portland cement and thus has a significantly lower CO2-footprint than conventional well cement. By replacing Portland cement with a low-emission well cementing material such as geopolymers, significant CO2 reductions can be achieved. The results show that metakaolin-based well cement can have potential as alternative well cementing material, which is promising. Moreover, this project has resulted in improved collaborations between Norway and Brazil, which may lead to additional similar, cross-Atlantic collaboration projects in the future.

All drilled wells are permanently abandoned when no longer being economically viable and reaching the end of their lifecycle. While previously seen as “something that will happen in the future”, permanent plugging and abandonment (P&A) of wells represents an increasing challenge on the Norwegian Continental Shelf and the backlog of wells is also building up in Brazil and other regions. As a result, the oil and gas industry is faced with a significant and costly cleanup job. More than 4,000 wells are set for P&A on the NCS alone at the cost of €m 4-40 per well. In Brazil, the regulator ANP points to 694 wells to be P&A’d already during the period 2021-2025. Cement and cementing operations contribute directly to but 5% of the total P&A costs. However, a failure of the operation or from using cement as material, can result in re-abandonment of the well and thus more than doubling the total P&A cost. Ordinary Portland Cement (OPC) is the prime material used today as zonal isolation material for primary cementing to maintain well integrity and P&A. OPC’s shortcomings are summarized in technical and environmental aspects, including an exceedingly high carbon footprint. Geopolymers (GPs) are a class of inorganic polymers made of aluminosilicate materials through polycondensation. GPs do not need calcination and are produced from natural minerals (“artificial rocks”). Generally, CO2 emissions of GPs are between 70-80% lower than OPC-based concrete. In this project, SafeRock AS (NO) and TECCIM Ltda (BR), in partnerships with the University of Stavanger and Universidade Federal do Rio Grande do Norte, plan to develop kaolin-based GPs for utilization in P&A for the O&G industry, with later potential also for CCS and geothermal wells. Mining companies and oil operator companies have joined the team as active sparring partners to mature technical and commercial aspects and support a future value chain, including Equinor and Petrobras.