Global Business Development, Cased Hole Services (Scientific Drilling International)
The evolution of geothermal casing inspection is a fascinating journey that spans a century of technological advancements, starting from the oil and gas industry and extending into modern geothermal applications.
The oil industry’s incipient well integrity industry
The story begins in 1898 with the birth of Macy Byron Kinley in Santa Barbara, California. Kinley worked in the oilfield from a young age under his father an oil well shooter who used explosives to stimulate oil in oil-bearing formations to flow. The often harsh and severe realities of the industry at the time were captured in the 2007 feature film “There Will Be Blood”. As the industry evolved, so did concerns for well integrity and well control. The younger Kinley’s career pivoted into the well control business, in which he became a pioneer alongside well control specialists such as Red Adair and Boots and Coots who learned the trade under him.
The analogue well surveying technology is born
Kinley was an inventor, with one of his inventions becoming a crucial tool in understanding well integrity and helping to reduce incidences of well control failure. The invention that stood the test of time was a caliper, deployed in the well on wireline, designed to measure the internal diameter of the borehole. The information gathered by the tool helped provide greater accuracy for cement volume calculations and gave an indication of the condition of downhole tubulars, aiding in the mitigation of compromised well integrity through the implementation of proactive remedial measures. Kinley was granted a patent for his ‘Well Surveying Device’ in 1937.
The device was, of course, devoid of any electronics or digital features with its functionality and mode of measurement based on mechanical systems. Essentially, the motion of the fingers drives a drum with a stylus responding proportionally to the fingers. The tool became an indispensable asset in the oil industry.
As well logging instruments continued to evolve toward greater sophistication, the Kinley caliper managed to retain relevance owing to its ability to operate at temperatures too high for electronic equipment. This feature did not go unnoticed in the geothermal industry. The Kinley calliper became the go-to well logging instrument for understanding the condition of geothermal wells without requiring quenching for wells with temperatures exceeding 300°C.
The Digital Caliper Arrives
Sophisticated multi-finger calliper technologies have been deployed by the oil and gas industry for decades. These instruments make diametrical measurements electronically and the data is stored digitally. Today, such sophistication is also available to the geothermal industry.
In 2020, Houston, Texas-based oilfield services provider and technology developer, Scientific Drilling International (SDI), commercialised a 40-finger electronic caliper that can operate at temperatures above 300°C while maintaining measurement specifications comparable to the most advanced oilfield caliper instruments. With this capability, high resolution and high accuracy measurements can be acquired revealing a detailed image of the condition of the casing and reliable statistical data for metal loss or scale deposition.
By the end of 2024, more than 150 runs had been completed for geothermal operators in the Far East and California, with demand continuing to grow exponentially.
Kenya’s growing geothermal industry can take advantage of the technology to enable better maintenance of geothermal wells. As the scale of geothermal operations grows, so does the necessity of regular monitoring of wells for potential causes of compromised well integrity or issues that can impede productivity. SDI looks forward to continuing its dialogue with Kenyan partners after its participation at the Kenya Geothermal Congress in July 2024 .
By Reza Khastoo Mr. Khastoo is a Product Line Manager, Cased Hole Services at Scientific Drilling International
