A breakthrough, achieved through the EU-funded I-DISC project, promises to save operators millions in operational costs. A new autonomous intelligent disconnect system uses electronic sensors and downhole processing to detect if drill parts have become stuck in the well, with systems that then allow the operator to command disconnection via a motorised clutch assembly. ‘The project now needs to be commercialised with the help of investment and operator acceptance of the new system,’ explains project coordinator Andy Ollerenshaw from Cutting & Wear Resistant Developments in the UK. ‘The savings that could be generated if this system is deployed compared to conventional disconnection methods could be in the many millions of dollars. Ultimately, this project could make difficult wells less expensive to exploit, and mitigate the risk of getting drill parts stuck.’ Challenging work environments Drilling an oil well is a complex engineering task that requires knowledge from an array of earth sciences, state of the art materials and creative thinking. ‘The business end of the drilling machine is called the Bottom Hole Assembly (BHA), which consists of the drilling tools and drill bit,’ explains Ollerenshaw. The drilling tools in the BHA give operators the ability to navigate the drill bit from the surface to a pre-selected target, which could be more than 10km from the surface location and at a depth of 5km depending on the subsurface target. The BHA also contains tools that constantly take measurements of the rock type and contained fluids (gas, oil, water) and transmit that data to surface in real time. There are many challenges in drilling a well to a specific point or target many kilometres below the surface. These include hitting the target (within a 50-metre radius for example), managing the high pressures and high temperatures, collapsing unstable rock and getting the drilling BHA stuck. The latter problem can be caused by poor hole cleaning i.e. the cut rock not being pumped out the hole quickly enough and accumulating around the BHA, preventing it being pulled out the hole back to surface. ‘This an expensive problem,’ says Ollerenshaw. ‘A drilling BHA can cost up to EUR 5 million. When a drilling BHA becomes stuck, the drilling pipe has to be disconnected from the BHA and recovered to surface.’ Present techniques involve running electric wireline explosives inside the drill pipe and detonating them as deep as possible to try and back off or blow off the drill pipe. This operation is fraught with technical difficulties and is expensive. Intelligent solutions The I-DISC project set out to provide a cost-effective solution to this issue by making hole cleaning and drill pipe disconnection easier, should the BHA become stuck. ‘From the outset it was clear that a completely new approach was required, involving new technology that makes use of artificial intelligence, sensors and electronic processing,’ says Ollerenshaw. The project focused on developing electronics and software capable of withstanding the tough downhole environment of high pressure, temperature and vibration. The technology also had to be reliable and able to address operational concerns of an accidental disconnect. This was achieved by including various modes that the tool has to recognise before progressing to the next mode, eventually ending up at disconnect mode. ‘We also had to make sure that the electro/mechanical clutch was strong enough to be able to transmit the forces required to the drill, but still provide a reliable actuation when required,’ says Ollerenshaw. The end result is an intelligent oil drilling application that gives operators greater control and peace of mind that should the BHA become stuck, a viable and cost-efficient solution is at hand.
I-DISC, oil, drill, BHA, drilling, technology, artificial intelligence, gas, water