L&TD

III. ANTI-COLLISION TO PRE-EXISTING WELLBORE WHILE DRILLING - ADVANCED SECURITY SYSTEM (ASS-2002):  

1. Introduction: 

   In drilling from offshore platforms there have been several cases where drilling a new well went directly into another neighboring production well and destroyed the casing of that well. This is due to very narrow well-to-well spacing (distance between the wells is 2.5-3.0m). So there is a demand to employ an Advanced Security System to detect this at an early stage before collision.

    The advanced security system detects the approach of the drill bit to casing of neibouring production wells. Data is sampled at high frequency from vibration sensors (Installed on well heads) and drilling sensors (WOH, RPM, TORQUE, SPP). The system uses the spectrum analyses of vibration signals by Fast Fourier Transform Algorithm. While drilling, if the drill bit   approaches a well then the is increasing and frequency of signal is concentrated in range of 300Hz - 700Hz. This phenomenon occurs more serverly with drilling parameter changes (eg: increasing of torque and/or decreasing of rate of penetration,..).

•  The system provides automated monitoring and detection of clash between the drill bit and casing of other neighboring production wells.

•  Internal Alarm Management (Set High /Low alarm, activates a buzzer when an alarm is detected).

• Printer management (Print out Real-time and Playback logs)
• Data management: Backup and store of Real-time database
• Calibration of the drilling sensors

      1. Introduction:

The ALS-2 Mud Logging Unit provides highly automated monitoring of the entire drilling operation. More than 70 parameters can be measured, processed, displayed, printed and recorded simultaneously. The acquisition system also calibrates the received signals and checks the state of the sensors for electrical faults such as a cut cable or open circuit. In the case of malfunction, an alarm is activated immediately alerting the operator.

For data processing a totally new concept has been adopted based entirely on computer technology. The sensor signals are transformed into digital format and then distributed according to requirement. The data is supplied on screen monitors (two types of screen system exist, the “Alpha-numeric” and the “Graphic”) or intelligent interfaces in real-time or playback mode. Alarms can be placed on each parameter. Computerized printouts of desired parameters produce graphic charts of the progress of the well being drilled. In addition the database is continually recorded on magnetic storage support.

The ALS is a powerful tool that may be placed in the hands of those with responsibility for the drilling rig. Using many forms of data presentation in the logging unit, monitors or intelligent interfaces can be placed anywhere on the rig. These terminals are “operator friendly” and enable anybody who needs information to have it right there in front of him in real-time or replay mode, and to apply analysis programs if necessary.

Off-line processing: An offline workstation is part of the ALS-2. This workstation has the following main functions:

•  Calibration of the sensors.
• Off-line calculations:

- Overpressure

- Hydraulics (Bingham, Power Law and other models)

- Deviation survey analysis

- Surge & Swab

- Drilling bit optimization

- Bit performance and cost

- Kick control

- Gas ratio analysis + plots

•  Data handling (graphic playback, log processing, import/export...)
• Diagnostic functions and network management.
• Reporting capabilities (word processing, graphics editor...)

2.1 Mudlogging Unit:

Mudllogging unit for offshore operation, complete with:

•  Air-condition System
•  Working area for client
•  Full UPS System to support all computers and data acquisition system
•  Airlock/Escape Hatch/MCT Entry
•  Pressurization system
•  Safety Equipment
•  Intercom system

•  Binocular Zoom (10 x 30) microscope
•  UV Fluoroscope
•  Sample Drying Oven
•  Geological Equipment and Chemicals
•  Sample Processing Trays
•  Shale Density
•  Autocancimeter

The FID (Flame Ionization Detector) Gas Detector & Chromatograph is a well site gas detection and analysis system. It continuously analyses gases extracted from the degasser.

• Measurement of total hydrocarbon gases in methane equivalents, with:
•  Measuring range: 250 ppm -100 %
•  Sensitivity: 200 ppm
•  Accuracy: 100 ppm
•  Calibration method: Manual

• Automatic chromatographic analysis of gas components (from C1 to nC5 measured in 240 seconds), with:
•  Measuring range: 30 ppm -100 %
•  Sensitivity: 20 ppm
•  Accuracy: 10 ppm
•  Calibration method: Manual injection.

2.4   Sensors and parameters:

Continuous analog recording on colour recorders and digital display on colour monitor of:

• Drilling rate, heave, depth, bit depth, TV depth, kelly height, hook height, footage, bit run, time on bit
• Weight on bit, hook load and over pull
• Individual pit volume and Totaliser (all active pits, trip tank and other pits)
• Pump rate and Totaliser (Flow in pumps), Lag time
• Standpipe Pressure, Well Head Pressure, Cement Unit Pressure
• Rotary RPM and Rev counter
• Mud temperature In/Out
• Rotary Torque
• Mud Flow Out
• H₂, H₂S, CO₂

Computer equipment consisting:

• Signal Conditioning Panel (SCP)
• Data Acquisition Panel (DAP)
• Real-time Monitoring Computer (RTM)
• Real Time Graphic Computer (RTG)

• Unit File Server (SVX)
• Off-line Computer (TDX)
• Real-time Printers
• Off-line Printer
• Repeater Monitor (for Coman & Rig floor)

• Reporting Daily Geological/Drilling Reports
• Reporting Daily Master Log/Over Pressure Log
• Submission of Client Approved Master Log, Pressure Evaluation Log (D-exponent).
• Submission of Client Approved Final Well Report at the end of each well.

           Same as other parts of L&TD, Mudlogging services have also been utilized in all Vietsovpetro wells. During drilling operations Mudlogging services perform the following functions: drilling operation monitor and control, geological data and information collection, drilling operation safety awareness.

For this work the MudLogging team has 24 highly trained and competant Engineers good experience in Mudlogging work. Most of them have more than 10 years working experience. In order to keep pace with new technological development, a number of relevant training courses are given to all staff to ensure that good quality service is achieved in all jobs.

At present, we are using the Geoservices ALS-2 Mud Logging Units (Advanced Logging System, second generation). In addition, we co-operate with domestic companies to design, manufacture and put Advanced Security System; into operation and upgrade & improve the completeness of equipment. Mud Logging Unit equipment is regularly replaced and upgraded in compliance with modern technology to secure operational correctness and stability.