Precise prediction of hydrocarbon burn efficiency is now possible

In the early 1900s, gushers were romanticized as symbols of prosperity. In retrospect, blowouts were recognized for their detrimental impact on personnel, assets and the environment, not to mention the loss of marketable resources. In response, well control technologies have evolved significantly over the last few decades, and Boots & Coots has been on the leading edge of those advancements.

Fig. 1. Myron Kinley is known as a trailblazer in the fire suppression industry. He developed many patents and designs for the tools and techniques of oil firefighting.

EARLY TECHNIQUES

Early in the industry, well fires could be extinguished using TNT, which depleted the available oxygen and effectively extinguished the conflagration, Fig. 1. Nowadays, the well is left to burn-off toxic elements, or voluntary ignition is used if the well has not caught fire spontaneously —the use of explosives is now confined to the annals of history. Burn efficiency modeling has matured significantly to determine just how critical it is to burn uncontrolled hydrocarbon emissions. Extensive industry leading research, involving Boots & Coots (Methodology to Predict Hydrocarbon Burn Efficiency of Blowout Flow in a Hostile Environment, SPE paper 062517), now enables precise quantitative prediction of how much is burned, and the quantity of asphaltenes that remain, assisting in determining suitable spill mitigation response.

With safety uppermost in the projects undertaken by the company, the work in Iraq after operation Desert Storm saw the introduction of the Athey Wagon as a less risky means of addressing the wellhead, either by cradling a venturi tube (Instrumented Venturi Tube, Boots & Coots, Patent application #2016-IPM-100655 U1 PCT) to vent the fire away from the immediate vicinity of the wellhead, or by supporting a new wellhead installation. With advances in wellhead operations came the addition of the jet cutter, that could cut through an existing wellhead more safely to prepare it remotely, rather than risk personnel near the blowing well. The cutter (Fig. 2), using a sand and water mixture, has been used by the company in the closer confines of platform fires, where limited space precludes the use of larger tools. The “Oxylance” has also become standard issue in recent years, to make more accurate cuts of the wellhead to prepare for re-heading.

Fig. 2. The sand-line cutter uses a sand and water mixture to suppress platform fires, where limited space precludes the use of larger tools.

RECENT ADVANCES

Focusing on prevention rather than cure, we supply the special services of gate valve drilling technology, hot tapping or a cryogenic freeze service, especially in cases where a well on production encounters problems. Gate valve drilling has progressed to the subsea environment, where we have IP to provide an ROV-driven system for deeper waters, where the environment precludes the use of divers (Deepwater Diverless Hot Tap Unit, Boots & Coots published invention disclosure #2017-IPM paper-101102).

Development of software algorithms has led to improvements in well-kill dynamics design, such as OLGA ABC and greater accuracy in kick tolerance using DrillBench. Likewise, updates in COMPASS software have allowed the firm to stay current with well planning techniques, and personnel have become power users of this industry-standard software, but that hasn’t stopped us from investigating more functional proprietary software designs of our own. Hand-in-hand with well kill, is well integrity, which is a preventative approach to well control, and has benefitted from using landmark software, such as StressCheck and WellCAT for casing design. Multiple well control scenarios can now be run in a relatively short timeframe, to determine the best ways to prevent well control incidents, especially in deepwater environments. The difficulty facing more mature wells is determining integrity. Older tubulars in a well must be de-rated, based on longevity and environment.

Gas dispersion and radiant heat modeling have become an aspect in the field of incident command and control – knowing how to set-up an incident site and work with local emergency response organizations to potentially move families that might otherwise be downwind of a burning rig, for example. Multi-well pad drilling with 20-ft to 40-ft, center-to-center well spacing, makes collaborative pre-planning well control essential. Risk mitigation is necessary as a pre-emptive tool, and we have been a proponent of risk evaluation as a progressive evolution in applying in-house expertise. The industry has emerged more proactively than it has been in years. The use of carefully constructed well control contingency plans is now regarded as an industry staple in the creation of the overall emergency response plan.

The magnetic guidance system (MGT), a tool for magnetic ranging applications, measures vertical and horizontal well separation between a relief well and a target well, within a precision of a few centimeters, for hydraulic interception during the well kill process. The MGT was developed in 1993 as a joint effort between Sperry Drilling and Vector Magnetics of Ithaca, N.Y. In 1999, further development work with rotating magnets was undertaken as another method of determining the proximity between a current well and a target well. Thus, the rotating magnet ranging service (RMRS) was born. The RMRS proximity surveys range from 5m to 15m behind the bit, combined with upgrades for shallow intersection and faster processing (2017). The addition of gyro measurements (2017) represent additional technological developments in relief-well drilling.

ELECTROMAGNETIC TELEMETRY

Since 2002, electromagnetic telemetry has seen the largest overall improvement in relief well ranging efficiency, minimizing the time impact and improving overall drilling efficiency (Electromagnetic Ranging Source Suitable for Use in a Drill String, Boots & Coots, U.S. Patent No. 9,534,488 B2). The need for a passive ranging tool that uses acoustic energy has been identified, particularly for real-time surveying. With a range to open hole, there is no ferromagnetic signal, or through salt domes, which otherwise absorb and scatter conventional magnetic ranging signals (Passive Ranging Using LWD Acoustic Velocity Measurements, Boots & Coots, Patent application #PCT/US2015/04940). Similarly, a means to range to a thermal signal, generated by the influx through the formation, is another area of investigation, when there is no steel present to provide a signal (Passive Ranging to a Target Well Using a Fiber Optic Ranging Assembly, Boots & Coots, Patent application #PCT/US2015/56484).

Fig. 3. The RapidCap AFCS 02 subsea capping system uses advanced computation, fluid-dynamic software to accurately model plume force velocities.

We embarked on a subsea source control solution in 2016, and operate an innovative capping stack, employing gate valve technology, a departure from more traditional, unwieldy ram-based systems (Method and System for Rapid Deployment of a Capping Stack, Boots & Coots, U.S. Patent No. 9,222,494 B2). The lighter design of the modular system can be deployed more rapidly to any global incident (Rapid Response Well Control Assembly, Boots & Coots, Patent filing 2016-IPM-100655 U1 PCT), compared to the logistically complex requirements that cumbersome, conventional capping stacks demand. The company is pushing further technological design change improvements (Ball Valve Design Capping Stack, Boots & Coots, Patent application #2017-IPM-101101 U1 PCT).

ENTER THE RAPIDCAP

Simulation software is taking the steadfast methods of subsea source control future-forward. Having branched-out into the subsea arena with the introduction of the RapidCap subsea capping system (Fig. 3), Boots & Coots is fast becoming industry leaders in capping stack deployment. Further technological features using ball-valve apparatus have already been submitted as a patent application. Sophisticated computational, fluid-dynamic software can accurately model plume force velocities and determine the veracity of landing a capping stack under any given condition.

Multibody interactions between the dynamic positioning deployment vessel, the heave compensated crane deploying the capping stack, the spring force produced by the deployment cable and the 6° of freedom of the capping stack, require massive computing power to produce a suitably high-resolution model accurately, and coupled with dynamic plume force analysis is adaptive rocket science. Additional groundbreaking research into the landing capabilities in both deepwater and shallow-water scenarios, a first in the industry, is being conducted solely at our discretion, Fig. 4.

Further investigation into slick propagation and migration from an oil spill, using smoothed particle hydrodynamics, is also being investigated. Predictive programs have existed for some time, but none have the accuracy or fidelity that is now being produced by a partner firm for slick dispersion analysis.

Fig. 4. The RapidCap AFCS 47 demonstrates landing capabilities in underwater scenarios and is currently undergoing research.

Alongside traditional well control methodology, our proficiency uses managed pressure drilling to precisely manage wellbore annular hydraulic pressure. Looking ahead, several field-proven, downhole data measurement technologies are being adapted to improve barrier integrity verification in subsea wells. Also included are wired casing for real-time monitoring of annular pressure/temperature during casing, cementing and production operations, wireless real-time annular pressure/temperature monitoring and fiber optic sensor measurement across producing formations (Casing/Tubing Annular Pressure/Fluid Expansion Control, Boots & Coots, U.S. Patent No. 9,835,009 B2).

IN SUMMARY

Well control has come a long way in the past 40 years. Our firm has grown into a technologically shrewd company that envisions improvements in data telemetry and “smart well” systems, new kick detection techniques and statistical algorithms. Those algorithms develop data trends and significant deviations from the expected measurement values, using sensitive, near-bit and pressure-while-drilling measurements from logging-while-drilling, to maximize the amount of time available to initiate well control and recovery procedures. We have embraced a proactive prevention ethos rather than concentrating on reactive response. But to aid in both facets, it has been imperative to move forward with the times, developing new techniques and innovation.