In today’s oil and gas markets, there are many drilling situations in which an operator faces adversity.
A growing difficulty to successfully and economically drill and produce wells has created a global demand for proper well optimization. Successful economical production of these wells requires a delicate balance between cost, performance, and risk. The oil and gas industry has a vast portfolio of available tools and technologies worldwide, with most aiming to provide new and improved information, save operators’ time, and improve the well’s profitability through various means of drilling optimization. The offshore markets also have additional inherent risks due to regulations and accident prevention. Utilizing existing and future technology to optimize this balance and leverage risk is the key to the next generation of drilling optimization; however, determining the correct method of optimization and required tools has historically depended on the application due to limited downhole information.
|Figure 1: NOV BlackBox downhole dynamics tool. Photo from NOV.|
There are many factors which lead to this drilling conservatism and inherent need for optimization, especially in today’s offshore wells. As the difficulty to reach a production zone increases, so does the risk. Many times the wells that are deemed more risky to produce also inherit a more conservative performance plan by operators. For years, the oil and gas industry has been adapting and upgrading tools, but the responsibility of the well inevitably requires human inter- action and decision making. Offshore drilling operators have invested millions of dollars into computerized technology and backup equipment to obtain the most precise measurements possible from surface equipment and prepare for any possible adverse downhole situations. Downhole tool configurations and bottomhole assembly (BHA) design also play a crucial role in this endeavor, yet deeper wells often take extended periods of time to transmit data back to surface, consequentially leading to a lack of knowledge of true downhole behavior at any given moment. There is a continual search for the perfectly balanced tool, one which produces high-performance data with low operator risk. How is this tool defined and who produces it?
To answer this search for the best drill- ing tool for well optimization, several aspects must be considered that highlight the future of the oil and gas industry, especially in offshore well production. Today’s drilling operators consider four main variables in drilling performance tools: speed, consistency, precision, and reliability, all at the lowest cost to increase production margins. Within these categories is the key to drilling optimization: A driller must have both the quality of data and quantity of data to make an informed decision. This comes with a caveat, as either of these variables alone is useless if it is not delivered quickly enough to surface for the driller to interpret. This adds increasing merit to the adoption of today’s technology into the industry.
The oil and gas industry has traditionally been slow to adapt to changes in technology, which will only be more scrutinized as the industry’s generation gap settles. There is a massive amount of experience leaving the industry, and the younger generation will rely more than ever on technology to capture, save, and utilize this information to bridge the knowledge gap in drilling. The most important aspect of this “crew change” will be the change in mindset, allowing the industry to progress its drilling optimization practices using digital technology and computer-controlled equipment as an aid to experience.
Because so many factors contribute to drilling optimization, a single tool would not alleviate the needs of the industry. Instead, a shift in the mindset of drilling practices toward using technology to facilitate decision making is a solution to the industry’s drilling optimization needs. The main catalyst driving this is technology integration.
As with other industries, operators will soon be faced with the “big data” situation—having the ability to visualize situations as they occur from various sensors integrated into drilling equipment both at surface and downhole. What can these sensors show, and how will they benefit today’s operators? The answer is a tiered approach, beginning with well planning and continuing through production, with each tier using these sensors in a related manner.
|Figure 2: Automated drilling system components. Image from NOV.|
There are various tools and drilling optimization solutions available in the market to complement this new tiered drilling mentality. First and foremost, there is proper well planning (survey data, formation expectations, and directional planning), which is the first step toward using downhole technology to increase performance and safety. Next, there is the ability to create a drilling roadmap, which is fully optimized for a particular region or series of wells. When establishing a pad to drill several wells, the operator typically drills the first well using only survey information. A drilling optimization tool (or series of tools in various locations in the BHA or string) such as National Oilwell Varco’s BlackBox memory tools (Figure 1) can record drilling dynamics data at a high frequency, as it occurs. This not only pro- vides the driller with valuable post-well drilling information, but also allows a drilling roadmap for the remainder of the pad. This roadmap can offer previously unknown details about the formation, reactive vibration and torque, and down- hole weight transfer, providing the driller with faster, more reliable performance going forward.
High-speed data telemetry with wired drillpipe supporting real-time downhole tools is at the top level of drilling optimization. When compared to traditional mud pulse measurement-while-drilling tools, real-time drilling data feedback can provide information to the surface at the fastest rate and highest quality possible, allowing the driller to visualize drilling reactions to the preplanned drilling road- map. This also allows for understanding of real-time energy loss based on the down- hole data versus surface data comparison.
Several wells have been drilled using National Oilwell Varco’s BlackStream downhole drilling dynamics tools in collaboration with IntelliServ wired drillpipe. While similar to the BlackBox memory tools in data acquired, the BlackStream downhole tools connect to wired drillpipe for real-time telemetry. Over the course of several wells, the BlackStream tools provided an increase in both consistency and performance. An illustration of the automated drilling system and components can be seen in Figure 2, showing the downhole tool and its connection to the surface data acquisition system.
The automated drilling system has several advantages with respect to drill- ing optimization. By itself, the system allowed the driller to clearly view downhole behaviors as they occurred while drilling. These behaviors allowed the driller to measure torque transfer and multiple types of vibration that were contributing to energy loss along the drillstring and BHA. While surface weight values were held relatively steady by using an autodriller, downhole weight values were very unpredictable and frequently oscillated above 50% of set point values on the wells drilled (SPE).
In addition to the driller’s ability to view downhole data, applications can also be implemented that connect to both downhole data and surface data, allow- ing for automated drilling. This application was activated on the surface data acquisition system during drilling and was able to collect downhole and surface data, acting as a “smart” downhole autodriller. This application used the data streaming to surface from the NOV BlackStream tools to calculate the most efficient operating values for various drilling equipment, keeping the down- hole behavior consistent and predictable. This consistency reduced the risk of tool failures while allowing for increased drilling performance and vibration consistency for the entirety of the well. Most importantly, this combination of tools and software led to increased reliability and safety.
With the increase of drilling hardware and software competition, tools must be properly chosen per application. Each tool has a specific purpose, and with the advent of real-time data telemetry to surface, it quickly becomes apparent which BHA combination is the most optimal. In the race to improve drilling performance and safety, consistency is winning. Sometimes less is more, and the key is finding the correct window of downhole weight, differential pressure, and rotations per minute (RPM) by trusting technology and software to guide and teach during the drilling process. A human may be able to make a single decision before a computer, but the long-term alert and automated damage mitigation of a proper data acquisition system will continually outperform a human in both speed and consistency.
Because the oil and gas industry has historically lagged other industries in regards to cutting-edge technology applications, there has been a growing separation between the oil and gas industry and other sectors in the race to computer- optimized performance and safety. This separation is rapidly decreasing, thanks to the advancement of technological oilfield equipment. There are increasing opportunities and growing excitement for improved offshore drilling techniques, but they will only become effective with the supporting mindset in the field and our willingness to trust in technology.
Pink, T., Koederitz, W.L., Barrie, A.K., Bert, D., Overgaard, D. 2013. Closed Loop Automation of Downhole Weight on Bit Improves Sliding Performance and Reduces Conservatism in Unconventional Horizontal Well Development. SPE 166428-MS.
Alex Barrie is product line champion for BlackBox tools at National Oilwell Varco, based in Houston. He manages the development and sustainability of drilling dynamics memory tools and is a subject matter expert of the product line. Previously, he worked with various groups collecting data from real-time automation tools, publishing and presenting the drilling optimization results to the oil and gas industry. Barrie earned a BS in mechanical engineering at Texas Tech University.