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 Trapped Gas in Horizontal Wells: What You Need to KnowIn horizontal wells, gas can sometimes become trapped in pockets within the wellbore. Due to buoyancy, gas tends to rise and gather on the high side of the hole when circulation slows or stops. This gas can remain in these pockets, such as washouts, when circulation resumes at a slow rate.In wells that are deviated at more than 90 degrees, gas might even migrate toward the bottom (toe) of the well. Unfortunately, these gas pockets can be difficult to remove when circulating at low rates, and they may only become dislodged later during drilling when pump rates resume to normal.To avoid these problems, it’s often recommended to use the Driller’s Method for well control in high-angle or extended-reach wells. This method involves starting the first circulation at a kill rate close to the normal drilling rate. This helps dislodge the trapped gas into the vertical section, preventing it from becoming an issue later on. By circulating at a higher rate initially, you can ensure that all the gas is safely evacuated.For more detailed information on trapped gas in horizontal wells,see my Well Control Manual V2.6 at: https://learn-well-control.com/product/well-control-manual-by-edwin-ritchie/ Read More

Managing Well Control During Trips: A Simple Action Plan Well control is vital in oil and gas drilling operations, especially when something unexpected happens. One common issue is when the well doesn’t take the right amount of fluid during a trip or begins to flow when the bit is off-bottom. These signs often mean that formation fluids (such as gas or oil) have entered the well, which could lead to a dangerous blowout if not handled quickly. This guide explains what steps a driller should take to control the well and prevent escalation, along with tips to avoid similar problems in the future.Immediate Actions When Hole Fill is Incorrect or Flow Occurs with the Bit Off BottomWhen a driller notices that the well isn’t taking the correct amount of fluid or that the well starts to flow with the bit off bottom, immediate action is necessary. These steps are crucial to prevent the situation from worsening.Stop Hoisting ImmediatelyThe first thing to do is stop lifting the drill string. If the string is raised, more formation fluid could enter the well, making the situation worse. Stopping hoisting helps slow down or stop the further influx of fluids.Perform a Flow CheckAfter stopping hoisting, the next step is to check for flow in the well. This helps determine if the well has become underbalanced (when the pressure inside the well is less than the pressure of the surrounding formation). The driller checks for fluid flow through the flowline or choke.If there’s no flow: The driller should return the bit to the bottom and start circulating the influx through the choke, effectively removing the unwanted fluid and regaining control.If there’s flow: This means the well is flowing, and immediate well control measures must be taken.Shut the Well InIf the well is flowing, the driller must quickly shut the well in to stop the flow. The driller should also inform the supervisor to keep everyone on the team aware and ready for further actions.Shut the Blowout Preventer (BOP): The driller should close the BOP as soon as possible to stop any further flow. The BOP, along with choke and kill systems, should be ready to use immediately.Strip Back to Bottom: If possible, the driller can lower the drill string back to the bottom of the well. Stripping means using the weight of the drill string to enter the well against a closed BOP (usually a annular BOP), while the pressure is controlled through the choke. This allows the influx expand in a controlled manner to minimize the wellbore pressure.Use the Choke: Once the string is back at the bottom and circulation is underway, the driller can use the choke to control the flow of fluids. The choke is essential for regulating the pressure and ensuring that the influx is safely removed from the wellbore.What to Do If Stripping Isn’t PossibleIn some cases, stripping might not be an option due to equipment limitations or other operational factors. If this happens, the driller can try these alternative methods Read More

The Density of Fluids and Its Impact on Pressure in Incompressible FluidsIntroductionThe density of a fluid plays a crucial role in determining the pressure exerted at a given depth within the fluid. Fluid density is a measure of how much mass is contained in a specific volume. In the context of diving or well operations, understanding fluid density helps to explain the variation in hydrostatic pressure with depth. This paper discusses how the density of fluids influences the pressure experienced at various depths, how it relates to the physical properties of the liquid, and how to calculate it. Hydrostatic Pressure and Fluid DensityHydrostatic pressure is the pressure exerted by a fluid at equilibrium due to the force of gravity. It increases with depth and is directly related to the density of the fluid. The formula for hydrostatic pressure in API units is given by:Hydrostatic Pressure (psi) = Mud Density (ppg) x 0.052 x TVD (ft) orHydrostatic Pressure (psi) = Pressure Gradient (psi/ft) x Depth (feet)For example, a diver at a depth of 10 feet in seawater with a pressure gradient of .455 psi/ft will experience a hydrostatic pressure of approximately 4.45 psi (.455 psi/ft x 10ft) in addition to the atmospheric pressure. In a freshwater lake at the same depth, the diver will only experience 4.33 psi (.433 psi/ft x 10ft). This difference in pressure arises because seawater is denser than freshwater and therefore has a higher pressure gradient. It is the increased salinity of the seawater that makes it heavier, resulting in a higher density and, consequently, a greater hydrostatic pressure.As the diver descends to 100 feet, the difference in pressure becomes more pronounced. In the ocean, the diver will experience 44.5 psi (.433 psi/ft x 100ft) of hydrostatic pressure, while in the lake, the pressure will be 43.3 psi (.433 psi/ft x 100ft). The added pressure is due to the relationship between the fluid’s density or gradient and depth. The greater the fluid density, the greater the pressure at any given depth.Impact of Depth and Fluid DensityThe pressure experienced by an object in a fluid increases with depth. However, this increase is not solely dependent on the depth itself but also on the density of the fluid. In a nearly incompressible fluid such as water, the pressure at any given depth is directly proportional to both the density of the fluid and the depth at which the pressure is measured. This is why seawater, being denser than freshwater, exerts a greater hydrostatic pressure at the same depth.Fluid Pressure in ContainersFluid pressure is independent of the shape or volume of the container holding the liquid. For example, if you submerge a pressure sensor at a certain depth in a fluid, the pressure it measures will be the same, regardless of the container’s shape or size. The pressure at that point is determined by the depth of the fluid and its density, not by the volume of fluid or the shape of the container.Direction of Fluid PressureIn a fluid, pressure is Read More

Well Control Emergency Drills: Their Importance and Effectiveness in Risk ReductionIntroductionWell control is a critical aspect of safe and efficient drilling operations. The ability to manage unexpected events, such as kicks or blowouts, is paramount to safeguarding both personnel and equipment.Emergency drills play a crucial role in well control by preparing the drilling crews to effectively respond to such situations. Norsok, a recognized standard for the oil and gas industry, emphasizes the importance of regular and realistic well control and emergency drills as a key tool for reducing risk and ensuring a successful response during an actual emergency.The Importance of Well Control and Emergency DrillsWell control drills are vital in reducing the likelihood of accidents by enhancing the competency of the crew and ensuring the functionality of the equipment. By practicing procedures that are typically non-routine, crews can familiarize themselves with emergency response protocols, improving their ability to handle real-life situations. Regular drills help to ensure that the crew’s skills remain sharp, reducing the chance of human error during critical moments.Norsok outlines several objectives for well control drills:Competence Development: Well control drills ensure rig personnel reach their expected level of competence to perform assigned tasks effectively.Skill Maintenance: They allow crews to maintain the required competency levels and be ready to react to emergency situations.Demonstration of Competency: Drills allow crews to demonstrate that they possess the necessary skills and knowledge.Equipment Verification: They help confirm that rig equipment is in good working order and suitable for well control operations.Documentation: Drills serve to document that crews possess the required competencies and that the equipment is fit for purpose.Types of Emergency DrillsA variety of emergency drills are essential to cover different aspects of well control. Some of the key drills include:Pit Drills: These drills train crews to respond to unanticipated changes in pit volume, either a pit gain (influx of formation fluids) or pit loss (overbalance). Regular practice ensures that the crew can quickly respond to prevent further problems, such as wellbore pressure imbalance or kick escalation.Trip Pipe Drills: These are designed to prepare crews for reacting to warning signs when the bit is off bottom. They help ensure that crews understand how to handle the situation and avoid the risks associated with tripping pipe.Strip Drills: These drills allow crews to practice complicated stripping-into-the-hole procedures, a critical operation when managing wellbore pressure during various stages of drilling.Choke Drills: Choke drills provide valuable practice in manipulating the choke during well control operations. Crews that perform choke drills regularly are more skilled at circulating out kicks and controlling influxes efficiently.Diverter Drills: Diverter drills are essential in training crews to react when a diverter is required, especially in situations where manual-sequencing diverters are used. These drills ensure that crews understand the correct procedures when dealing with well kicks or pressure issues when a BOP (Blowout Preventer) stack is not yet installed. Regular diverter drills should be performed daily when drilling in conditions where a diverter may be needed.BOP Drills: These drills focus on the operation of Blowout Read More

What is Kick Intensity? Kick intensity in drilling refers to the degree of underbalance in the wellbore, which occurs when the pressure exerted by the drilling fluid is lower than the pressure exerted by the formation fluids. The greater the difference between the pressure in the wellbore (due to the mud weight) and the formation pressure, the more intense the kick. The intensity of the kick impacts the speed and volume of the influx of formation fluids into the wellbore, which can be critical for the well’s safety. In practical terms, kick intensity is related to how much the formation pressure exceeds the pressure exerted by the drilling fluid, and this imbalance is directly tied to the risk of a blowout. The pressure difference is typically measured in terms of pounds per gallon (ppg) or kilograms per cubic meter (kg/m³) for mud weight, or in pounds per square inch (psi) or kilopascals (kPa) for pressure measurements. For more information on Kick Intensity as it relates to well control visit: https://learn-well-control.com/product/well-control-manual-by-edwin-ritchie/ Read More