Drilling for Success: 2 Statistical Approaches to Assess and Improve Drilling Inefficiencies

Joshua Zable | 6/28/2023

Topics: Minitab Workspace, Oil & Gas

In the oil business there are two things a large multinational corporation, a national oil company, an independent oil company, an oilfield services company and an independent contractor have in common:

  • They all want to quickly optimize their output with the least amount of cost.
  • They all face challenges that create drilling inefficiencies that challenge their ability to execute their goal.

Why the Inefficiencies?

There can be several reasons why an oil company may experience inefficiencies in drilling operations.

Geological Challenges

Drilling operations can be affected by complex geological formations, such as hard rock formations, high-pressure zones or unexpected subsurface conditions. These challenges can lead to slower drilling progress, increased wear on drilling equipment and the need for frequent equipment maintenance or replacement.

Equipment Limitations

Inefficient or outdated drilling equipment can hinder drilling operations. Equipment malfunctions, inadequate power or torque, limited drilling speed or insufficient drilling fluid circulation capacity can all contribute to inefficiencies in the drilling process.

Inadequate Planning and Execution

Poor planning and coordination can lead to inefficient drilling operations. Inaccurate well design, improper selection of drilling techniques, inadequate wellbore stability measures and inadequate supervision and communication can result in delays, increased costs and suboptimal drilling performance.

Suboptimal Drilling Fluid Properties

The properties of the drilling fluid, such as viscosity, density, lubricity and stability play a crucial role in drilling efficiency. Using inappropriate or poorly formulated drilling fluids can cause issues such as stuck pipe, differential sticking, poor hole cleaning or excessive wear on drilling tools, leading to reduced drilling efficiency.

Safety and Regulatory Compliance

Stringent safety and environmental regulations in the oil and gas industry can sometimes add complexity to drilling operations. Companies that struggle with maintaining compliance or fail to implement effective safety practices may experience delays or interruptions in drilling activities, leading to inefficiencies.

Data Analysis Can Identify Areas of Improvement to Reduce and Eliminate InEfficiencies

Collecting and analyzing relevant data during drilling operations can help identify the inefficiencies. Without it, the company may miss potential optimizations, best practices and lessons learned that could enhance drilling efficiency.

As an example, imagine that an oil company wants to assess and improve its drilling process in terms of drilling speed, specifically the time it takes to drill to a certain depth. The company’s target is to drill to a certain depth within 12 hours. The company has collected data on drilling times for a sample of wells drilled in a particular field.

It collects the hours of drilling time from 30 wells as follows: 12.5, 10.9, 11.8, 13.2, 11.5, 12.1, 11.3, 12.7, 13.5, 14.2, 10.8, 12.0, 13.1, 12.3, 11.6, 12.8, 11.9, 12.4, 13.0, 12.6, 11.2, 13.3, 12.9, 12.6, 11.7, 13.8, 12.5, 12.2, 10.7, 11.4.

Descriptive Statistics and Visualizations Can Lead To Insights

While this is a basic first step, by calculating certain descriptive statistics, such as mean, median, standard deviation and range, one can obtain an overview of the data and identify any outliers or unusual patterns.

Based on the data in our example, the mean and median are both between 12 and 12.5 hours, which indicates our data is symmetrical or fits a normal distribution. Looking at a histogram, we can see a picture of our distribution, including identifying outliers.

However, on average, the company is not meeting its specifications of 12 hours.

There are two opportunities for improvement: First, identify the oil wells that took over 12 hours may highlight inefficiencies that exist. Second, by figuring out what went right in the oil wells that took less time than the mean and median, there is an opportunity to apply those learnings to other wells.

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While there are clearly opportunities for improvement, before we tinker with our process, let’s better understand whether or not its stable and capable of replicating results.

Analysis of The Process Can Indicate If the Process is Stable And Capable of Meeting Targets Consistently

Using Minitab’s proprietary Process Capability Six Pack, with one quick click of a mouse we can see control charts which highlight that our process is stable. Unfortunately, both our Cpk and Ppk are close to zero, highlighting that our process is not capable. For a process to be capable, your Cpk and Ppk should be at least greater than 1.33, ideally a value of 2.0 or higher where possible.

Understanding this is critical to improvement; it informs us that our process cannot meet specifications. Rather than trying to make a change on one of the wells, we should be evaluating our entire drilling process.

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What’s Next? Begin an Improvement Project!

Understanding a process needs improvement is the first step in a continuous improvement exercise. Using project planning and execution tools, like those found in Minitab Workspace, you can map out and assess your process. From there, collect data for analysis and use statistics and predictive analytics to help you identify root causes of your issue.

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