MPD Monitoring Technique Allows Rapid Redesign, Flexibility
Authors: Carpenter Chris 
Published: September 2019

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 194097, “Real-Time MPD Optimization in Challenging Scenarios,” by Guilherme Siqueira Vanni, SPE, André Alonso Fernandes, Gleber Tacio Teixeira, Antonio Carlos Vieira Martins Lage, André Leibsohn Martins, SPE, and Felipe de Souza Terra, Petrobras, and Marcelo de Souza Cruz, Fabio Rodrigues G. da Silva, and Cristiano édio Dannenhauer, Engineering Simulation and Scientific Software, prepared for the 2019 SPE/IADC International Drilling Conference and Exhibition, The Hague, 5–7 March. The paper has not been peer reviewed.

This work focuses on the development of specific methodologies to support managed-pressure-drilling (MPD) operations implemented on real-time diagnostic software. The developed methodology proposes as output ideal operating parameters, such as choke pressure, pump-flow rate, or adjustments related to drilling-fluid properties. The methodology considers the best approach to meet the restrictions imposed by the operational window. The real-time optimization procedures proposed are a further step to ensure reliability of MPD operations in challenging scenarios.

Real-Time MPD Optimization

Specific modules were developed from a drilling-problem diagnostic software to provide real-time support for MPD operations. The primary advance represented by these modules is the consolidation, in a computational tool, of MPD best practices. The tool, which uses real-time drilling data as input, will propose and enable immediate action in the event of anomalous situations or ones not predicted in project planning.

Dynamic Pore-Pressure Test (DPPT) and Dynamic Formation Integrity (DFIT) Procedures. These procedures allow a more-accurate estimate of values for pore and fracture pressures, respectively. These procedures are suited particularly for drilling in narrow operating window scenario, because they allow correction of geological-profile data obtained previously with current field geopressure. Thus, the probability of gain and loss events becomes smaller in an MPD operation when compared with a conventional drilling scenario.

During these tests, in each pressure step performed in the choke, the software calculates the volume balance related to the compression or decompression of the fluid in the well. The software calculates the volume that decreased from the active tank (DFIT) or increased in the active tank (DPPT). The software also calculates the volume balance related to the compression (DFIT) or decompression (DPPT) of the fluid in the well. These calculations determine whether these volume variations, both real and expected, follow the same magnitude. The difference between them is the criterion used to stop both procedures (DPPT and DFIT).

In Petrobras’ drilling operations, this proposed limit normally is set to 2 bbl. This preset threshold is a minimum acceptable value to consider that a gain or loss is occurring. If this difference surpasses the limit value, the module triggers a message warning the rig crew.

After these procedures, the simulator updates the operating window, using real downhole data [effective circulating density (ECD)] in a conservative way. The logic adopted for updating is to use the largest value between the DPPT and the value of the pore gradient present on the project. For the fracture gradient, inverse logic is adopted; the lowest value between the DFIT and the fracture gradient obtained on the project is used. Fig. 1 illustrates the pore-gradient update.