GTS (well testing)

Test Your Knowledge

Quiz: GTS (Well Testing) in Oil & Gas

Instructions: Choose the best answer for each question.

1. What does GTS stand for in the context of well testing?

a) Gas to Surface b) Ground to Surface c) Gas to System d) Global Temperature System

2. Which of the following parameters is NOT typically measured during GTS testing?

a) Flow rate b) Pressure c) Water content d) Temperature

3. Why is GTS testing important for reservoir characterization?

a) It helps determine the volume of oil in the reservoir. b) It provides insights into the reservoir's pressure, volume, and composition. c) It helps identify the type of rocks present in the reservoir. d) It measures the amount of water in the reservoir.

4. What is a primary objective of GTS testing in terms of well performance evaluation?

a) Determining the well's age. b) Assessing the well's productivity. c) Measuring the well's depth. d) Identifying the well's location.

5. Which of the following is NOT a typical step involved in GTS testing?

a) Well preparation b) Flow rate measurement c) Seismic analysis d) Data analysis

Exercise: GTS Data Analysis

Scenario: A GTS test was conducted on a well, and the following data was collected:

• Flow Rate: 10,000 cubic meters per day (m3/day)
• Wellhead Pressure: 250 bar
• Gas Composition: 90% Methane, 5% Ethane, 3% Propane, 2% Other

Task:

1. Calculate the daily production volume of methane (m3/day).
2. Explain how this data can be used for production optimization and reservoir characterization.

Techniques

Chapter 1: Techniques for Gas to Surface (GTS) Well Testing

This chapter delves into the various techniques employed in GTS well testing, exploring their functionalities, advantages, and limitations.

1.1 Flow Rate Measurement:

• Differential Pressure Flow Meters: These meters measure the pressure drop across an orifice plate or venturi to determine the flow rate. They are widely used due to their accuracy and reliability, especially at high flow rates.
• Turbine Meters: These meters measure the speed of a turbine spinning within the gas stream, which is directly proportional to the flow rate. They are known for their high accuracy and low pressure drop but are typically used for lower flow rates.
• Ultrasonic Meters: These meters measure the transit time of ultrasonic waves through the gas stream, which varies with the flow velocity. They are non-invasive and can be used for both clean and dirty gas streams.

1.2 Pressure Measurement:

• Pressure Gauges: These gauges measure the pressure at specific points along the flow path using mechanical or electronic sensors. They are widely available and relatively inexpensive.
• Pressure Transducers: These transducers convert pressure readings into electrical signals, providing accurate and continuous pressure data. They are often used in conjunction with data acquisition systems for real-time monitoring.

1.3 Composition Analysis:

• Gas Chromatography: This technique separates the different gas components based on their boiling points and measures their relative concentrations. It is highly accurate and provides detailed information on the gas composition.
• Mass Spectrometry: This technique measures the mass-to-charge ratio of ions produced from the gas sample, enabling the identification and quantification of different components. It is particularly useful for identifying trace gases.

1.4 Temperature Measurement:

• Thermometers: Traditional mercury or alcohol thermometers are still used for simple temperature measurements.
• Thermocouples: These devices measure temperature by converting the electromotive force generated by two dissimilar metals into a temperature reading. They offer high accuracy and are widely used in GTS testing.
• Resistance Temperature Detectors (RTDs): These devices measure temperature based on the change in electrical resistance of a metal wire. They are known for their high precision and stability.

1.5 Data Acquisition and Analysis:

• Data Acquisition Systems: These systems collect, store, and process data from multiple sensors, including flow meters, pressure transducers, and thermometers. They provide real-time monitoring and analysis capabilities.
• Software Analysis: Specialized software packages are available for analyzing GTS data, including flow rate calculations, pressure drop calculations, and gas composition analysis. These tools facilitate interpretation and decision-making.

1.6 Specialized Techniques:

• Multiphase Flow Measurement: This technique is used to measure the flow of gas, oil, and water simultaneously, which is crucial for accurate reservoir characterization and production optimization.
• Isotope Analysis: This technique analyzes the isotopic ratios of different gas components to identify the origin of the gas and understand its migration path.

This chapter provides a comprehensive overview of the diverse techniques used in GTS well testing, empowering readers to understand the methodologies behind data acquisition and analysis.