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Managed Pressure Drilling is a process that uses a closed-loop circulation system for more accurate bottom hole pressure control, resulting in higher drilling efficiency and the prevention of drilling hazards. More operators are turning to IPT to validate the integrity of critical equipment and ensure that the benefits of Managed Pressure Drilling are realized.
In conventional (onshore) drilling, the circulating system operates in a flow path that is open to the atmosphere. To control the well, drilling engineers adjust the mud density and may also use the equivalent circulating density (ECD) to maintain the bottom hole pressure (BHP) within a drilling margin determined by the formation’s pore pressure and fracture pressure (Figure 1). After the mud exits the top of the wellbore, it goes through a flowline to mud-gas separation and solids control equipment before being recirculated in the well. When the pumps are circulating mud in the hole, the BHP is a function of the hydrostatic pressure plus the annular friction pressure of the mud. When the pumps are turned off to make connections, the BHP is controlled solely by the hydrostatic pressure of the mud in the hole.
Drilling using an open circulating system presents challenges to control BHP in deep wells. First, small changes in mud density have a large impact on the hydrostatic pressure. Also, deep wells have high annular friction losses, resulting in large changes in BHP when the pumps are turned off. If the BHP becomes greater than the hydrostatic pressure of the mud, an influx of formation fluids can create a kick. The driller tries to control a kick by adjusting the mud density and shutting in the well to monitor the pressure. Then the driller circulates the kick out of the hole at a slow pump rate. The repeated cycles to kill the well and circulate out the kick significantly increases non-productive time (NPT) and safety risks.
Drilling margins are narrower in deepwater where the overburden pressure of seawater is less than that of rock and the formation strength is lower (Figure 2). As a result, it is standard practice in deepwater to set numerous casing strings at shallow depths to avoid extensive lost circulation.
Managed Pressure Drilling (MPD) is a closed circulation system that allows drillers to monitor the wellbore’s annular hydraulic pressure profile more accurately and react in real time to precisely control BHP. The annular hydraulic pressure is maintained slightly above the pore pressure to prevent the influx of formation fluids and also well below the fracture pressure to avoid loss of circulation. Preventing these hazards improves safety and greatly reduces NPT in complex wells by increasing operational drilling efficiencies. MPD makes access to older depleted reservoirs possible and allows operators to drill previously “undrillable” wells. MPD can also reduce the number of casing strings required, thereby reducing trips and saving time, in addition to allowing a well to be completed in a larger hole size.
IPT works closely with operators, rig contractors, and Managed Pressure Drilling contractors to develop strategies that optimize test planning and execution. Typically, Managed Pressure Drilling component validation can be accomplished with relatively few additional tests during commissioning and BOP testing. IPT ensures that the required number, frequency, and types of tests are run to validate component integrity, avoid equipment-related NPT, and comply with local regulatory bodies.
SureTec allows existing BOP schematics to be used or modified for MPD test plans. SureTec’s Schematic Editor validates all connections and component names, making it easier to detect and correct errors compared to using complex rig piping and instrumentation diagrams (P&IDs). SureTec’s Plan Editor clearly identifies the test criteria, valve alignment, pressure path, and MPD components that will be validated in each test step.
SureTec uses proprietary algorithms and stringent criteria capable of validating MPD component integrity at low pressure to significantly reduce pressurized time and increase integrity assurance. SureTec’s advanced validation algorithms, such as Thermally Compensated Leak Detection (TCLD) are available in the Advanced and Premier tiers of SureTec.
SureTec generates standardized, detailed planning and test reports with complete documentation of test steps including pressure graphs, analysis charts, schematics, and tested components. IPT’s SureView Portal lets organizations archive and retrieve tests and analyze test results to share best practices and drive performance across teams.
Contact us today to find out how our team and applications can help you design, execute, and optimize your MPD program.