Petrobras Uses NI LabVIEW to Develop a High Throughput Mud-Gas Separator for Underbalanced Drilling

Author(s):
Manoel Feliciano da Silva - Petrobras

Industry:
Oil and Gas/ Refining/ Chemicals

Products:
LabVIEW

The Challenge:
Developing a mud-gas separator for underbalanced drilling that improves efficiency and flexibility.

The Solution:
Using National Instruments LabVIEW to design a compact, cost-effective HMI/SCADA system capable of faster time to production.

Underbalanced drilling (UBD) is an innovative drilling technique in which hydrodynamic pressure, exerted by the drilling mud and circulating fluids in the well bore, is below the pressure of the well formation. In UBD applications the surface pressure is lower than the well pressure, resulting in the flow of hydrocarbons to the surface at a controlled rate. This drilling technique requires specialized surface equipment for continuous separation of the drilling mud and hydrocarbon components for recirculation, sampling, storage, flaring, and disposal. UBD technology provides significant technical and economical value and reduces damage to the well formation.

Petrobras has deployed UBD technology in the field for more than two and half years. This technology is cost-effective because we are able to reduce the time required to reach full production and eliminate, or at least reduce, the fracturing required after a well is completed. In traditional drilling, pressure often causes formation damage and delays full production or forces the drilling company to perform a fracturing job on the well.

By deploying UBD technology based on NI LabVIEW, we save between $500,000 and $2 million depending on the size of the well and the cost of a fracturing job.

Real-Time Mud-Gas Separation Technology

The mud-gas separation system for UBD continuously separates a multiphase fluid consisting of gas, liquid, cuttings, and drilling mud before recycling the drilling mud into the well bore. System requirements include:

• Compact design that can handle high flow rates of gas and liquid
• Dynamic response to injected or produced variations in gas flow rates and pressures
• Support for nonstandard flow phenomena when drilling with compressible fluids

We designed a vertical-pressure operating helical separator, equipped with an automatic supervisory and control system based on LabVIEW and National Instruments data acquisition products. We developed two versions of the system: one for land operations and one for offshore operations. This case study details the acquisition and control system for land operations.

System Overview

The mud-gas separation system uses an HMI/SCADA application, Aleph, which we designed using LabVIEW; a microcomputer that runs the LabVIEW application; drivers for integration with other programmable logic controllers (PLCs); and screens for operator control of the UBD operation.

Aleph and LabVIEW provide process diagram visualization, separator measurements, and real-time control loops for the continuous separation. The data acquisition system measures:

• Drill bit position through an electromagnetic measurement while drilling (EM MWD)
• Gas and liquid flow rates
• Liquid height and pressure within the separator
• Downhole pressure measurements and control valve positions through intrinsically safe sensors and transmitters capable of 4-20 mA

LabVIEW also provides connectivity to the drilling control PLC through an RS-232 serial drive and connectivity to a remote system through a DataSocket server. The system meets all design requirements including:

• Safety – intrinsically safe sensors and a separate UBD control PLC
• Flexibility – flexible software and modular hardware for additional I/O
• Integration – open protocols and LabVIEW software with a wide range of connectivity
• Ease-of-use – LabVIEW graphical development environment

Aleph System Modes of Operation

The system operates with three modes: server, client, and playback. The server located in the control room connects to the data acquisition system, to other PLCs through a LabVIEW serial, and to remote clients using a DataSocket server for communication. The server also performs historical data logging and historical trending. The client accesses server data through a remote Web connection and operates remotely while providing remote viewing and printing at local stations. A playback mode gives managers, engineers, and operators the ability to record and playback data for field performance postanalysis and operator training.

High-Speed Measurements Critical for Dynamic System

The mud-gas separator we developed delivers a compact separation system that can handle the dynamic gas and liquid flow rates generated during drilling with compressible fluids, and responds quickly to variations in the pressure or flow rates from injected or produced variations in the dynamic systems. The LabVIEW HMI/SCADA relies on high-speed measurements of system phenomenon including flow rates, pressures, and temperature to determine control setpoints and then sends these setpoints to the control PLC through the LabVIEW serial driver. Real-time measurements and trending provide operators with better data for decision making and improved safety along the drilling operations.

Using LabVIEW and the measurement capability of National Instruments, we developed a compact and flexible system that performs continous separation of mud and gas in UBD applications. With the flexibility of LabVIEW, we can connect to existing PLCs; perform high-speed measurements; and provide necessary server, client, and playback modes needed with the HMI/SCADA system. We tested and approved the equipment for land operation during full-scale experiments in Taquipe-BA and during real field operations in four oil wells drilled at Estreito Field.

For more information, contact:

Manoel Feliciano da Silva, Jr.

Petrobras

Tel: +55 21 38656538

Fax: +55 21 38656735

E-mail: Feliciano@petrobras.com.br

 

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