The drilling industry continues to push the limits of its technologies in order to access deeper, hotter, higher-pressure reservoirs. As the industry moves toward drilling wells where surface pressures may top 20,000 psi – or “extreme HPHT wells” – it must ensure its capability to manage unexpected well control events.
Such high-pressure wells typically involve a multitude of factors during the well construction process, and there can often be a high degree of uncertainty when interpreting commonly available data. Therefore, even after following time-consuming procedures to properly understand a situation, doubts may remain about whether a certain condition requires non-standard control action. This can lead to decisions that add significant costs or unnecessarily threaten to stop the well short of its target.
Well control challenges associated with extreme HPHT operations may include:
- Narrow safe operating “windows”;
- High wellbore temperatures;
- Fluid compressibility issues;
- Mud rheology challenges;
- Relatively high equivalent circulating density (ECD) effects in long, small-diameter hole sections;
- Large wellbore fluid volumes requiring long displacement time; and
- Surface equipment complications/limitations.
SafeKick’s SafeVision Well Control Package was developed to provide benefits during conventional well control operations, but its features may also help to manage extreme HPHT wells.
The SafeVision package does not stop working when a well is shut-in on a kick; data is continuously provided while the secondary well control system is being used to control wells containing surface pressures up to the full pressure rating of the rig’s well control equipment. This makes it possible to differentiate a real sustainable kick from a false kick. It also allows for the use of dynamic processes to circulate suspected or real influx volumes to surface through the advanced, automated choke.
The system also makes it possible to quantify and take advantage of high circulation rate friction pressures, thereby widening the pressure window available during kill operations. It may even permit circulation rates sufficient to allow utilization of downhole tools, such as PWD or LWD instruments, to assist in assuring successful management of bottomhole pressures.
The ability of the system to facilitate instant, on-site forward simulations based on existing well conditions – including temperature, density, geometry and cuttings load transients – makes possible evaluation of non-standard well control practices before implementing them. This could improve safety and efficiency of well control operations.
When used properly in conjunction with teams of local and/or remote well control, operations and risk management resource personnel – all of whom have the same situation-critical information displayed the same way by the system at the same time – new well control approaches become possible.
Because even small increases in the circulation rate have large proportional effects on the time required for well control-related circulations, there is a surprisingly large benefit to using kill rates that would never be permissible without adequate real-time modeling, flow-out measurements and high-performance/reliability choke control. Current dependence on slow kill rates may be causing excessive NPT. Avoiding this dependence may help the industry to control the costs of drilling extreme HPHT wells. In other words, while efficiency must not take priority over operational safety, there is little point in pursuing targets with processes too inefficient to permit commercial success.
Fortunately, from a drilling well control perspective, managing a well with truly extreme pressures acting on surface equipment will almost surely depend mostly on containment during shut-in and subsequent high-pressure bullheading operations. It remains very unlikely that there will ever be a need for regular crews to use a rig’s standard well control equipment, such as its rig chokes, to dynamically control wells with truly extreme surface pressures. The focus of secondary well control procedures will and should remain on the planning, training and execution of procedures necessary to avoid preventable escalation of technically controllable situations.
SafeVision: The Driller’s GPS
Our software products are designed to provide prioritized, common information to all individuals both on and off the rig. SafeVision, our base software platform, helps solve the problem of data overload by utilizing intelligent processing of common rig drilling data to display, in a very intuitive format, a simulation of conditions in the well below the rig floor.
In the same way that a GPS can help a driver, it enables those in control of drilling operations to make efficient, timely decisions. SafeVision is available in three different, but related versions to meet different drilling management needs.
SafeVision Standalone Package
This core product allows users to “drill the well on the simulator”, displaying with clear and simple graphics various critical relationships occurring below the rig floor.The heart of the program is an advanced, fully transient hydraulics module optimized to quickly simulate complex wellbore relationships.The common display (all packages) contains prioritized information rather than excessive raw data. The emphasis is on providing a thorough overview of current well status using a depth-based graph linked to a detailed well sketch. Display of logged (time based) data is optional and may be customized by the user.
SafeVision Office Package
This product uses data collected from rig sensors to permit the simulator to model and display current well conditions. By taking snapshots of transient well conditions, the system allows users to forward simulate, thereby facilitating review of alternative future outcomes.When linked to current rig operation via SafeLink, the display makes offsite monitoring easy, facilitating good decision making involving all the right people.By storing processed, rather than raw data, it is also possible to archive drilling data for quick review and replay following important events.
SafeVision Rig Package
The Rig Package allows for a new level of integration of information and automation that is not typically available today. Once installed, the Rig Package allows for data to be read directly from rig sensors or control systems. The system provides customized data displays and simulations based on the specific configuration of the rig.The Rig Package also allows for integration into rig systems to provide a level of control that cannot be currently obtained through manual operation. Typical rig equipment that the Rig Package can interact with include:
- Well control choke
- Mud gas separator
- Valves along different fluid paths
- Mud pumps (under development)
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