Three chemical strategies for drilling through clay formations. Understanding which approach suits your ground conditions is the difference between a smooth bore and a stuck drill string.
The Challenge
Clay formations cause bit balling, mud rings, clay sausages, and stuck pipe — but each is caused by a different mechanism. Bit balling results from dispersed clay re-agglomerating on tooling. Swelling is caused by water contacting clay platelets. Adhesion is a surface chemistry problem. Using the wrong product for the wrong mechanism wastes product and leaves the real problem unsolved.
The Approach
Three chemical strategies address different mechanisms. Encapsulation (Clay Stop PHPA): long-chain polymer coats clay cuttings, preventing adhesion and stringing. Dispersion (Clay Dissolve): penetrates and breaks down clay structures, effective against bit balling and mud rings. Inhibition (Clay Control): prevents water from contacting clay platelets, migrating through filtrate into surrounding formations for pre-treatment. Supporting products — Detergent for wetting, Torque Down for lubricity, Carry Flow for suspension of heavier cuttings — complete the system.
The Outcome
Drilling fluids work best as preventative measures. Having the right drilling fluids from project commencement maximises the likelihood of a stress-free and successful installation. The right chemical combination — matched to the specific clay mechanism at work — eliminates reactive on-site changes and keeps the bore stable from start to finish.
The Full Story
Drilling in clay formations can be challenging. Tooling choice and methodology are important contributors to the successful drilling of clays.
Equally important (and our focus here) is looking into drilling fluid chemicals that can help with this formation type.
What are we trying to achieve when drilling in clays?
1. Giving free available water a job
Clay loves water. When drilling, we use a lot of water for various reasons. When we use drilling fluid products, we tie up the loose water that is available for the clay to consume and react. We give the water a job by making it tied up in the chemical program, meaning there is less free water available for the clay to drink and react.
2. What are our core clay product additive chemical functions?
- PHPA-based polymer (Clay Stop liquid or dry) encapsulates clay cuttings, keeping them free from sticking to other cuttings and creating problems down the hole. It also 'strings' up on borehole walls, contributing to some lubricity.
- A thinner or dispersant (Clay Dissolve) penetrates and breaks clays down. It has the greatest impact on bit balling, mud rings, or clay sausages and is highly effective at stripping down clays and the viscosity associated with them.
- An inhibitor (Clay Control) significantly affects swelling and reactive clays. It creates a barrier that prevents water from making contact with the clay/bentonite at the platelet level, which has a major impact on preventing those clays from swelling and spreading. In solution, this chemical also migrates into the formation through the filtrate. So, if your drill program has you stepping up hole sizes, the formation already has some chemical inhibition to it.
- Other associated clay-based products. Detergent for wetting or further penetrating clays, also washing tooling. Torque Down for premium lubrication, lining tooling for maximum lubricity makes it difficult for clays to stick to tooling. Carry Flow for suspension, since not all clay cuttings are light, fluffy and walk out of the hole; using a suspension enhancement product to increase our carrying capacity (yield point) always adds value.
Drilling fluids are always best viewed as a preventative component of the drilling process. Having the right drilling fluids from project commencement maximises the likelihood of a stress-free and successful installation.
Having the right chemicals in the system or onboard at the site for changes means we can keep the formation and cuttings in their most manageable state.
Most drillers use 'mud programs' or 'fluid recipes'. We at Blick are here to optimise the above products to suit the formation, the program or profile being undertaken and the methodology.