A kick is an unwanted influx of formation fluids into the wellbore during drilling, which can lead to serious well control problems and blowouts. To prevent or handle kicks, you need to incorporate kick detection and control into your well design and drilling program. Here are some key aspects to consider.
Kick tolerance is the maximum volume and pressure of gas that can enter the wellbore without exceeding the fracture gradient of the weakest formation. It depends on the pore pressure, fracture gradient, mud weight, casing depth, and well geometry. You need to calculate the kick tolerance for each section of the well and design the casing program accordingly. You also need to monitor the kick tolerance during drilling and adjust the mud weight if necessary.
Hole size, BHA and drill pipe outer diameters also are important. Kick tolerance is driven by the true vertical height of the influx (usual assuming pure gas) and subsequently converted to an equivalent volume in the annulus.
From design to operations, the well design must consider the worst case scenario for the open hole section when a kick of a certain volume is taken with corresponding surface pressure, known as the maximum initial shut in casing pressure (MISICP) beyond which the weak point in the open hole (not always the shoe) will fail. Operationally any kick taken must have a lower volume and corresponding surface pressure to enable circulation and still be below this MISICP, otherwise the weak point will fail. The TVD height of the influx assumed to be gas for worse case drives the surface pressure behavior. Well deviation, BHA open hole annular clearance, circulation rate, kick intensity, fluid type, temperature etc all impact the influx behavior.
Some other considerations: A. Kick Tolerance is calculated for a specific drilling fluid density and true vertical drill (bit) depth below the last casing shoe depth (which is generally assumed to be the weakest point in the openhole). B. Calculated Kick Tolerance ALWAYS DECREASES with increasing: 1. vertical drill depth and/or 2. drilling fluid density. C. If calculated Kick Tolerance decreases to a value close to the driller's realistic ability to detect and stop the influx, it's time to stop drilling ahead and consider setting casing before drilling into the next permeable formation interval.
Seems like the existing methods of kick detection are manual. What do you think how Artificial Intelligence algorithm can help advancing the Kick detection system in real time?
Kick indicators are signs that formation fluids are entering the wellbore, such as changes in mud flow rate, mud level, pit volume, standpipe pressure, drill pipe pressure, and torque and drag. You need to install and calibrate the proper sensors and instruments to measure these parameters and display them in real time at the rig floor and the driller's cabin. You also need to train the drilling crew to recognize and report the kick indicators and follow the appropriate procedures.
Connection gas observation is an excellent indication of entering an under balanced mode while drilling. The ECD holds back the “influx” until pumps are shut down for connections. As connection gas levels rise, so does the under balance, and eventually ECD will be insufficient to prevent flow, then background gas levels will rise. Encounter some permeability, and a kick will occur.
Additionally you need the sensors to not be ignored. Too many systems send false alarms and end up getting silenced because crew members are not situationally aware. Advances in AI and ML from Pason, NOV and Nabors help with this
Additional indications, especially of a slow flow, include changes in salinity and other mud theology properties and temperature of returned mud.
Services companies need to develop better, smarter algorithms based on AI, ML and other approaches to improve current alarms for potential kick indicators. Based on experience the detection factor (% of true kick detection alarms) must be at least 75-80% to be considered useful. It is annoyed and overwhelming to get an alarm every 5 minutes or faster for events that are normally not kick indicators and take away precious time from you. I feel this is antes where the room for improvement is huge
Kick detection systems are software or hardware tools that analyze the kick indicators and alert the driller of a possible kick. Some examples are flow meters, pit level indicators, pressure transducers, and mud logging units. You need to select the best kick detection system for your well and integrate it with the rig control system and the data acquisition system. You also need to test the kick detection system regularly and verify its accuracy and reliability.
Managed pressure drilling is both an effective way to accurately identify a kick, and as a means of extending the primary well control window. By creating a closed system with the wellbore, any additional volume from a kick will naturally increase the outlet pressure which can be detected by the MPD system. As long as the pressure require to stop the flow and the gas flow rate at surface is less than the safe operating pressure of the MPD system, there is no need to active the BOP and revert to secondary well control. This can save significant rig time.
Kick detection systems that rely on pit levels should be VERY cautious. I have published a lot of data that shows the actual volumes reported by pit-volume-totalizers is significantly off, regularly by 20% or more. Rig pressure sensors have also been shown to be unreliable and operators should require a validation and verification program for these safety critical measurements. Liquid proving pit volumes only needs to be done every 5-10 years. Calibrating pressure sensors is cheap and easy. Doing these will save a life one day--maybe yours.
One of them would be flow back and must take fingerprinting flow back before drilling the new section. Take fingerprint with different flow rate. And also compare the active pits before and after connection.
Kick control methods are techniques to stop the influx of formation fluids and restore the hydrostatic pressure in the wellbore. The most common method is the driller's method, which consists of two circulation cycles: one to circulate out the kick with the original mud weight, and another to circulate in a heavier mud weight to balance the formation pressure. Other methods include the wait and weight method, the volumetric method, and the bullheading method. You need to choose the most suitable kick control method for your well and simulate it with a well control software. You also need to have a contingency plan in case the kick control method fails.
Kick prevention equipment are devices that prevent or limit the flow of formation fluids into the wellbore, such as blowout preventers (BOPs), choke and kill lines, and mud-gas separators. You need to install and maintain the appropriate kick prevention equipment for your well and comply with the safety and environmental regulations. You also need to conduct regular pressure tests and function tests on the kick prevention equipment and document the results.
Blowout preventers (BOPs), choke and kill lines, and mud-gas separators are not kick prevention equipment. Blowout prevention, yes. Kick prevention equipment include salinity levels, gas detection, PWD sensors, etc.
A new device that may automatically close an annulus by the kick flow could help to simplify the process. The technology is covered by a newly approved US patent 11,441,388. The device may also automatically control a blowout and it is intended to work without human attention.
Kick management practices are policies and procedures that ensure a safe and efficient response to a kick situation, such as well control manuals, emergency response plans, well control drills, and incident reporting. You need to develop and implement the best kick management practices for your well and communicate them to all the stakeholders. You also need to train and certify the drilling personnel on the kick management practices and conduct audits and reviews to evaluate their performance.
I don't disagree with the points raised but would like to add that by using a competent predrill PP prediction and then realtime monitoring for PP you can reduce the number of kicks and a problem avoided is better than a probelm solved.
Early detection of any unwanted fluids to the system will reduce lost time ! Small kick…. small ??! Detection method need to be in place and validated as operations continue
Effective team communication is critical between rig and office based personnel is vital. There is no well control situation that during post event analysis, the cause or causes stand out and you wonder why didn’t someone see it.