Stick Plot

Stick Plot: The Stick Figure Story of Your Well

In the world of oil and gas exploration, a "stick plot" isn't a children's drawing, but a powerful visual tool that reveals the hidden stories within a well. It essentially translates the data from a dip meter, a device used to measure the dip and strike of geological formations encountered during drilling. This information is vital for understanding the structural complexities of the reservoir and optimizing production.

The Stick Plot: A Visual Representation of Dip Meter Data

A stick plot is a graphical representation of the dip and strike measurements obtained from a dip meter. It's a simplified illustration, hence the "stick" analogy. The plot typically shows:

Depth: The vertical axis represents the depth of the borehole.
Dip: The angle of inclination of the geological formation relative to the horizontal is plotted using lines, often colored or shaded to represent different rock types or formation characteristics.
Strike: The direction of the formation's horizontal extent is represented by arrows or other symbols.

Decoding the Stick Plot: What it Tells Us

By analyzing a stick plot, geologists and engineers can deduce critical information about the reservoir:

Structure: The dip and strike values reveal the geometry of the formations, whether they are folded, faulted, or tilted. This helps to understand the potential for oil and gas accumulation.
Reservoir Continuity: By tracking the dip and strike across different depths, we can assess the continuity of the reservoir. This is essential for predicting the extent of the hydrocarbon deposits.
Production Optimization: Understanding the reservoir's geometry allows for more efficient well placement and completion strategies, maximizing production and minimizing risks.
Fault Identification: Changes in dip and strike can indicate the presence of faults, which may act as barriers to fluid flow or create pathways for oil and gas migration.

Dip Meter Results: The Foundation of the Stick Plot

The dip meter itself is a downhole tool that measures the inclination and azimuth of the borehole. It uses magnetic or acoustic sensors to identify the direction of the earth's magnetic field or sound waves, which are affected by the orientation of the rock formations. This data is then translated into the stick plot for visual analysis.

The Stick Plot: A Vital Tool in Oil & Gas Exploration and Production

The stick plot is an indispensable tool for geologists and engineers working in the oil and gas industry. It provides a clear, concise visualization of the subsurface geology, allowing for:

Informed decision-making: It enables optimal well placement and completion strategies, minimizing risks and maximizing production.
Reservoir characterization: It helps to understand the complex structural features of the reservoir, leading to better resource estimates and production predictions.
Exploration and development planning: It provides valuable insights for targeting new exploration areas and optimizing existing production operations.

In short, the stick plot, fueled by dip meter results, paints a detailed picture of the reservoir's hidden world, guiding the exploration and exploitation of valuable hydrocarbon resources.

Test Your Knowledge

Stick Plot Quiz:

Instructions: Choose the best answer for each question.

1. What is the primary purpose of a stick plot in oil and gas exploration?

a) To illustrate the physical characteristics of the drilling rig. b) To visualize the dip and strike of geological formations encountered during drilling. c) To track the progress of a well drilling operation. d) To map the distribution of different rock types in the subsurface.

Answer

b) To visualize the dip and strike of geological formations encountered during drilling.

2. What information is NOT typically represented on a stick plot?

a) Depth of the borehole b) Dip of the geological formations c) Strike of the geological formations d) Estimated volume of oil and gas reserves

Answer

d) Estimated volume of oil and gas reserves

3. How does a stick plot help geologists understand the structure of a reservoir?

a) By showing the location of faults and fractures. b) By indicating the presence of oil and gas deposits. c) By revealing the geometry of the formations, whether folded, faulted, or tilted. d) By predicting the flow rate of hydrocarbons from the reservoir.

Answer

c) By revealing the geometry of the formations, whether folded, faulted, or tilted.

4. What type of downhole tool provides the data used to create a stick plot?

a) Logging tool b) Dip meter c) Seismic sensor d) Core sampler

Answer

b) Dip meter

5. Which of the following is NOT a benefit of using a stick plot in oil and gas exploration and production?

a) Optimized well placement b) Improved reservoir characterization c) Enhanced drilling speed d) More efficient exploration and development planning

Answer

c) Enhanced drilling speed

Stick Plot Exercise:

Scenario: You are a geologist analyzing a stick plot from a well drilled in a sedimentary basin. The stick plot shows a series of dips and strikes indicating a folded formation. The dip angle increases significantly at a particular depth, followed by a sudden change in strike direction.

Task:

Interpret the potential geological structures indicated by the changes in dip and strike.
Explain how these structures could impact the exploration and development of the reservoir.
Suggest further investigations that could be carried out to refine the understanding of the reservoir's geometry.

Exercise Correction

1. Interpretation of Geological Structures: - **Increase in Dip Angle:** The increase in dip angle suggests a possible anticline (upward fold) or a fault block tilting upwards. - **Change in Strike Direction:** The change in strike direction likely indicates a fault cutting through the formation. 2. Impact on Exploration and Development: - **Anticline or Fault Block:** These structures could create traps for oil and gas accumulation, making the area a potential target for exploration. - **Fault:** The fault could act as a barrier to fluid flow or create a pathway for migration, affecting the distribution of hydrocarbons. - **Further Investigations:** - **Seismic data:** To confirm the presence and geometry of the structures and assess their potential for hydrocarbon accumulation. - **Additional well data:** Drilling additional wells in the area could provide more detailed information about the reservoir's structure and characteristics. - **Core analysis:** Analyzing rock cores from the well could provide information on the lithology and reservoir properties, helping to understand the potential for production.

Books

Petroleum Geology: This classic textbook by William D. "Bill" Dott Jr. and David E. Dott provides comprehensive coverage of geological principles applied to petroleum exploration, including sections on structural geology, reservoir characterization, and well logging techniques.
Applied Subsurface Geology: By John C. Davis, this book focuses on the practical application of geological concepts in the oil and gas industry, with detailed explanations of well log interpretation, geological modeling, and seismic interpretation.
Well Logging and Formation Evaluation: This book by Schlumberger, a leading provider of oilfield services, offers a thorough explanation of well logging techniques, including dip meter technology, data processing, and interpretation of stick plots.

Articles

"Dipmeter Surveys: A Powerful Tool for Subsurface Analysis" (Journal of Petroleum Technology, 2004): This article explores the importance of dipmeter surveys in understanding reservoir geometry and structural complexities, highlighting the role of stick plots in interpreting data.
"Stick Plots: A Visual Guide to Subsurface Structures" (Geo-Scientist Magazine, 2015): This article focuses on the practical application of stick plots, discussing the interpretation of dip and strike values, recognizing geological features like folds, faults, and unconformities, and using this information for reservoir characterization.
"The Importance of Dipmeter Data in Reservoir Modeling" (SPE Journal, 2010): This article emphasizes the role of dip meter data in creating accurate reservoir models for production simulation, demonstrating the critical link between stick plot interpretation and well performance predictions.

Online Resources

Schlumberger's "Dipmeter" webpage: This webpage provides a detailed overview of dipmeter technology, including its working principles, types of tools, and applications in various geological environments.
Halliburton's "Well Log Interpretation" webpage: This webpage offers a wealth of information on well log interpretation, including dedicated sections on dip meter data, stick plot analysis, and their implications for reservoir characterization.
SPE (Society of Petroleum Engineers) website: Search their extensive database of technical papers for articles focused on "dip meter", "stick plot", and "reservoir characterization" for more in-depth studies and specific case studies.

Search Tips

Use specific search terms like "stick plot interpretation", "dipmeter analysis", "reservoir characterization using dip meter", or "well log interpretation software".
Include the name of specific oilfield service companies like Schlumberger, Halliburton, Baker Hughes, or Weatherford in your search.
Use advanced search operators like "site:spe.org" to target specific websites or "filetype:pdf" to find downloadable publications.

Techniques

Stick Plot: A Comprehensive Guide

Here's a breakdown of the information into separate chapters, expanding on the provided text:

Chapter 1: Techniques for Obtaining Dip Meter Data and Constructing Stick Plots

This chapter delves into the practical aspects of acquiring and interpreting dip meter data.

1.1 Dip Meter Types and Operation: We'll discuss various dip meter technologies, including:

Magnetic Dip Meters: How they utilize the Earth's magnetic field to determine formation dip and strike. Limitations due to magnetic anomalies will be addressed.
Acoustic Dip Meters: Explanation of how sonic waves are used to measure formation dip. Advantages and disadvantages compared to magnetic methods will be explored.
Combination Dip Meters: The benefits of integrating both magnetic and acoustic data to improve accuracy and overcome limitations of individual methods will be examined.

1.2 Data Acquisition and Quality Control: This section focuses on:

Logging procedures: Detailed steps involved in running a dip meter log, ensuring proper tool orientation and data acquisition.
Data cleaning and processing: Techniques used to remove noise and correct for borehole deviations and other sources of error.
Data validation: Methods for verifying the quality and reliability of the acquired data.

1.3 Constructing the Stick Plot: This section outlines the steps involved in creating a stick plot from processed dip meter data:

Data visualization software: Introduction to different software packages used for creating stick plots.
Choosing a suitable scale and representation: Discussing various options for visually representing dip and strike information, including line thickness, color coding, and arrow styles.
Incorporating additional data: Methods for integrating other well log data (e.g., gamma ray, porosity) into the stick plot to enhance interpretation.

Chapter 2: Geological Models and Interpretations from Stick Plots

This chapter focuses on using stick plots to build geological models.

2.1 Structural Interpretation: This section examines how stick plots reveal structural features:

Fault identification and characterization: Recognizing faults based on abrupt changes in dip and strike. Determining fault type, displacement, and orientation.
Fold analysis: Interpreting fold geometry (e.g., anticlines, synclines) and their impact on reservoir geometry.
Stratigraphic correlation: Using stick plots to correlate formations across different wells and build a 3D geological model.

2.2 Reservoir Characterization: This section explores how stick plots contribute to reservoir understanding:

Reservoir geometry: Determining the extent, shape, and thickness of reservoir layers.
Reservoir connectivity: Assessing the continuity and potential for fluid flow within the reservoir.
Structural traps: Identifying potential hydrocarbon traps based on structural features revealed in the stick plot.

Chapter 3: Software and Tools for Stick Plot Analysis

This chapter provides an overview of available software and tools.

3.1 Commercial Software Packages: A review of industry-standard software used for processing dip meter data and creating stick plots, including their functionalities and capabilities. Examples might include Petrel, Kingdom, and Schlumberger's interpretation software.

3.2 Open-Source and Free Alternatives: Exploring open-source or free software packages that can be used for similar purposes.

3.3 Data Import and Export Formats: Discussing the common data formats used in the industry for dip meter data and stick plot creation and sharing (e.g., LAS, LIS).

Chapter 4: Best Practices for Stick Plot Interpretation and Application

This chapter offers guidelines for effective use of stick plots.

4.1 Integrating Multiple Data Sources: Emphasizing the importance of integrating dip meter data with other geological and geophysical data for a more comprehensive interpretation.

4.2 Uncertainty and Error Analysis: Discussing methods for quantifying uncertainty in dip meter measurements and their impact on interpretations.

4.3 Collaborative Interpretation: Highlighting the value of collaborative interpretation by multiple geoscientists to improve accuracy and reduce bias.

4.4 Avoiding Common Pitfalls: Identifying and discussing common mistakes in interpreting stick plots and strategies for mitigating these issues.

Chapter 5: Case Studies: Real-World Applications of Stick Plots

This chapter illustrates the practical use of stick plots with examples.

5.1 Case Study 1: A detailed analysis of a specific well's stick plot, demonstrating how the interpretation led to improved well planning and production optimization. Include images and diagrams.

5.2 Case Study 2: A case study highlighting the role of stick plots in identifying and characterizing a fault system impacting hydrocarbon accumulation. Include images and diagrams.

5.3 Case Study 3 (Optional): Another case study showcasing a different geological setting and the unique challenges and successes in interpreting the stick plot.

This expanded structure provides a more complete and informative guide to stick plots in the oil and gas industry. Remember to include relevant images and diagrams throughout to enhance understanding.

Similar Terms

Reservoir Engineering