Saucier Criteria

Test Your Knowledge

Quiz: Understanding the Saucier Criteria

Instructions: Choose the best answer for each question.

1. What is the primary purpose of gravel packing in oil and gas wells?

a) To increase wellbore pressure b) To enhance fluid flow c) To prevent formation sand from entering the well d) To stimulate reservoir production

2. What is the "D50" value in the context of Saucier Criteria?

a) The median grain size of the gravel pack b) The maximum particle size of the formation sand c) The particle size at which 50% of the formation sand is retained d) The total weight of the formation sand sample

3. According to the Saucier Criteria, how is the recommended median gravel size calculated?

a) D50 multiplied by 3 b) D50 divided by 2 c) D50 multiplied by 6 d) D50 divided by 4

4. Which of the following is NOT a benefit of using the Saucier Criteria for gravel pack design?

a) Simplicity and ease of use b) Efficiency in determining gravel size c) Accuracy in predicting gravel pack performance d) Reliability based on proven applications

5. What is a significant limitation of the Saucier Criteria?

a) It does not consider the type of drilling fluid used b) It requires extensive laboratory analysis c) It does not account for all factors influencing gravel pack performance d) It is not applicable to horizontal wells

Exercise: Gravel Pack Design

Scenario: You have a well with formation sand having a D50 value of 0.25 mm. You want to use the Saucier Criteria to determine the recommended median gravel size for the pack.

Task:

1. Calculate the recommended median gravel size using the Saucier Criteria.
2. Discuss two other factors you would consider in addition to the Saucier Criteria for designing the optimal gravel pack.

Techniques

Understanding the Saucier Criteria: A Practical Guide to Gravel Pack Sizing in Oil & Gas

This expanded guide breaks down the Saucier Criteria into separate chapters for better understanding.

Chapter 1: Techniques

The Saucier Criteria is a technique for determining the appropriate median gravel size for gravel packing in oil and gas wells. It's a relatively straightforward method that relies on a sieve analysis of the formation sand to determine its particle size distribution. The core technique involves:

1. Sieve Analysis: A representative sample of formation sand is sieved using a set of sieves with progressively smaller mesh sizes. The weight of sand retained on each sieve is recorded.

2. Cumulative Percentage Retained Curve: The data from the sieve analysis is used to construct a cumulative percentage retained curve. This curve plots the cumulative percentage of sand retained against the sieve size.

3. D50 Determination: The D50 (median particle size) is identified on the curve. This is the particle size at which 50% of the sand is retained and 50% has passed through.

4. Gravel Size Calculation: The Saucier Criteria dictates that the median gravel size (D_g50) is six times the D50 of the formation sand: D_g50 = 6 * D50. This factor of 6 provides a safety margin to prevent sand production while maintaining sufficient permeability.

Chapter 2: Models

While the Saucier Criteria itself isn't a model in the traditional sense (like a complex numerical simulation), it acts as a simplified empirical model. It assumes a linear relationship between the formation sand's D50 and the required gravel pack size. This simplification ignores many factors that influence gravel pack performance in reality. More sophisticated models exist that incorporate these factors, such as:

• Discrete Element Method (DEM): DEM simulations can model the interaction between individual sand and gravel particles under various stress conditions, providing a more accurate prediction of gravel pack behavior.
• Finite Element Method (FEM): FEM can model the stress and strain within the gravel pack and surrounding formation, helping to optimize pack design for different well conditions.
• Empirical correlations: More complex correlations incorporating factors like formation permeability, fluid viscosity, and wellbore geometry can provide a refined estimation of required gravel size.

These advanced models offer greater accuracy but require significantly more computational power and input data compared to the simple Saucier Criteria.

Chapter 3: Software

Several software packages can assist in gravel pack design, some incorporating advanced modeling techniques and others streamlining the Saucier Criteria calculations. These tools can automate the analysis of sieve data, generate cumulative percentage retained curves, and calculate the recommended gravel size based on the Saucier Criteria or more sophisticated models. Examples might include reservoir simulation software (e.g., Eclipse, CMG) with specialized gravel pack modules, or dedicated well completion design software. Spreadsheet software can also be used to perform the basic calculations of the Saucier Criteria.

Chapter 4: Best Practices

While the Saucier Criteria offers a starting point, best practices for gravel pack design extend beyond simple calculations:

• Representative Sampling: Obtain a truly representative sample of the formation sand for accurate sieve analysis.
• Multiple Sieve Analyses: Perform multiple sieve analyses to ensure data reliability and account for potential variations in formation sand properties.
• Consider Formation Properties: Account for formation permeability, porosity, and other relevant properties that can impact gravel pack performance.
• Wellbore Conditions: Consider wellbore diameter, casing size, and other completion details that may affect gravel pack design and placement.
• Fluid Dynamics: Evaluate the impact of fluid flow rates and fluid properties on gravel pack performance.
• Gravel Properties: Select gravel with appropriate properties such as size distribution, sphericity, and strength.
• Quality Control: Implement rigorous quality control measures during gravel pack installation to ensure the pack is properly placed and compacted.
• Post-Completion Analysis: Monitor well performance after gravel pack installation to evaluate its effectiveness and identify any potential issues.

Chapter 5: Case Studies

Case studies are essential to demonstrating the application and limitations of the Saucier Criteria. These would detail specific well scenarios, including formation characteristics, chosen gravel size (determined via Saucier Criteria and potentially refined by other methods), and the ultimate success or failure of the gravel pack in preventing sand production and maintaining well productivity. Analyzing case studies helps to understand when the Saucier Criteria is sufficient and when more complex models are necessary. Successful case studies would show the effectiveness of the Saucier criteria in providing a suitable initial gravel pack size, while unsuccessful case studies could highlight scenarios where the simplified approach leads to issues. These could involve over- or undersized gravel, leading to reduced permeability or sand production respectively.