Reservoir Engineering

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:

  1. Interpret the potential geological structures indicated by the changes in dip and strike.
  2. Explain how these structures could impact the exploration and development of the reservoir.
  3. 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.

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Reservoir EngineeringDrilling & Well CompletionOil & Gas ProcessingProject Planning & SchedulingGeology & Exploration
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