Nabors Industries has raised the bar in circulation technologies through its subsidiary Canrig Drilling Technology. The Non Stop Driller is a sub-based system which enables the constant circulation of drill fluids downhole, while making or breaking drill pipe connections. The system has been designed to rig up quickly and efficiently with minimal interference to normal rig operations, improving wellbore stability and hole cleaning, reducing nuisance gas circulation and the risk of kicks, and optimizing drilling performance. Each stand to be drilled down requires a pre-installed sub. When the stand is drilled, the Non Stop Driller sub is used to create a side entry access point to the drill string. The system utilizes a high-pressure mud hose with an integrated quick connect mechanism to create a high-integrity connection to the drill pipe. A proprietary locking mechanism eliminates the possibility of hose release during drilling operations. An HMI-controlled remote manifold incorporating multiple safeguards and system interlocks is used to redirect the flow path of the drilling mud through the side entry valve in the Non Stop Driller sub. Once the flow is redirected, the ball valve at the top of the Non Stop Driller sub is closed to isolate drill string pressure, allowing constant circulation during connections. When the connection is completed, the flow of drilling mud is redirected through the top drive and drilling continues.
Non Stop Driller can assist to either stop the use of nitrogen, or minimizing its consumption. Additionally, this device eliminates the need to rely on time-consuming practices, such as circulating or reaming before every connection, as well as post-connection stabilization time during the multiphase drilling on air, foam, and two-phase wells. The Non Stop Driller is able to withstand excessive bottomhole temperatures and mitigate bottomhole assembly heat soak damage. The connection valve uses a protective cap rated for 10,000psi to prevent damage while being deployed in the wellbore. The primary metal-metal seal rated for 30,000psi also provides a secondary barrier to wellbore fluid. Other wellhole improvements include enhanced hole cleaning, continuous solids transport, and a consistent annular pressure profile across the entire wellbore, eliminating stability problems. According to Nabors’ collected data, the Non Stop Driller can increase drilling efficiency by 50%. A single connection usually takes from 15 minutes to one hour, while this tool can carry out the job in seven minutes. In terms of safety, users do not have to open up the connection or face unbalanced columns, which can prevent blow outs, or at the other extreme, mud losses in the well. With the Non Stop Driller, the columns of the well are balanced, which is essential for integrity, making the casing run smoothly.