Oil well control is one of the most important aspects of drilling operations. Improper handling of kicks in oil well control can result in blowouts with very grave consequences, including the loss of valuable resources. Even though the cost of a blowout (as a result of improper/no oil well control) can easily reach several millions of US dollars, the monetary loss is not as serious as the other damages that can occur: irreparable damage to the environment, waste of valuable resources, ruined equipment, and most importantly, the safety and lives of personnel on the drilling rig.
In addition to containing kicks and preventing blowouts oil well control procedures can cover a variety of other downhole conditions. For example, drillbit speed, torque and direction must be controlled during drilling, as well as the weight on bit (WOB). The flow of drilling mud and the density of the mud are also controlled, so that when WOB and cutting removal by the drilling mud are optimized and the rate-of-penetration (ROP) by the drillbit may also be optimized.
A number of downhole devices placed in close proximity to the drill bit measure certain downhole parameters associated with the drilling and downhole conditions. Such devices typically include sensors for measuring downhole temperatures and pressures, azimuth and inclination measuring devices, and a resistivity-measuring device to determine the presence of hydrocarbons and water.
As the drilling bit travels down through the formation, the geology will change and additional downhole instruments, known as logging-while-drilling (“LWD”) and/or measurement-while drilling (“MWD”) tools, are frequently attached to the drillstring to determine the formation geology and formation fluid conditions during the drilling operations.
As the downhole operating conditions change and the operator must react to such changes and adjust the surface-controlled parameters to optimize the drilling operations. Usually, the drilling operator monitors the downhole conditions via the various sensor readings on as display, attempts to identify the occurrence of undesirable downhole conditions, and then takes action at the surface by adjusting one or more of the surface-controlled drilling parameters, to mitigate the undesirable condition.
Accordingly, this conventional approach seeks to manually address the downhole issues as or after they arise. In some cases, by the time the drilling operator has recognized the downhole problem and altered the surface-controlled drilling parameters, expensive damage to the drillstring, the drill bit, and/or other downhole components has already occurred.
Some drilling operations employ predictive models that receive data relating to surface and/or downhole conditions and output a set of recommended values for the drilling parameters (e.g., bit RPM) based on analysis of such measurements. The recommended drilling parameters may be implemented manually or via automated control systems. However, the physics behind such modeling schemes is complex, and typically depend on accurate measurements of surface and downhole conditions, which are often difficult to obtain in the harsh drilling environment. Consequently, some of the predictive models are less effective than desired.
Software has been designed to monitor and report the various conditions that need to be monitored and adjusted to during the various drilling and oil recovery operations. US20120217067, for example describes a software program that collects data and based on a comparison of the measured data with the well plan models, and a comparison of the measured data with the minimum and maximum values for each drilling parameter, the processor determines if any adjustments are necessary to maintain the current well plan, and displays status and warning information via displays. Similar software-based oilwell control systems are disclosed in U.S. Pat. No. 8,332,153, U.S. Pat. No. 7,729,895, U.S. Pat. No. 6,820,702, US20120123756, US20120139747, US20100193245, and the like.
However, most of these programs only require a warning signal to be visually displayed, thus requiring the operator to continuously monitor the display, although for dangerous indicators, like a kick, the software may implement an automated response such as immediate shut in and adding the required kill weight of mud to kill the flow.
Even if an audible warning signal is incorporated into the software, such alarms provide no information about the quality of the hazard, nor which remedial action(s) would be appropriate. Thus, valuable time can be lost as the operator ascertains the nature of the hazard and the appropriate reaction.
Thus, what is needed in the art are better methods of monitoring well drilling completion and production conditions, and in particular better methods of warning operators about potential hazards and provides the appropriate remedial steps. This disclosure addresses one or more of those needs.