Multilateral Technology Then and Now

The first multilateral technology patent was filed in 1929 and was followed by additional patents.

Many of us can cite epochs in the petroleum industry’s history. But often not so memorable is the evolution of technologies that seem new and “cutting edge” but actually have a long history of development. A case in point is multilaterals. You may be surprised to learn that the first multilateral technology patent was filed in 1929 and was followed by additional patents and rudimentary attempts to drill multilateral wells in the 1930s. 

Some sources credit Leo Ranney with being the first to try horizontals and multilaterals in the United States. Ranney, a Canadian, was a consulting engineer in Texas and Oklahoma. In 1925, he developed the Ranney method of using horizontal wells to extract oil from exhausted fields. Standard Oil Company of New Jersey bought out his patent and made him president of Ranney Oil and Mining Company, a subsidiary of Standard Oil from 1930 to 1938. In 1939, Ranney drilled an 8 ft (2.44 m) vertical shaft in Ohio, put men and equipment in the bottom of the hole and drilled a horizontal section. He is also reported to have drilled in a horizontal radial pattern like the spokes of a wheel, establishing probably the first multilateral with horizontal sections.

After the war, an inventor, John A. Zublin, drilled horizontal “drainholes” for operators in California. In 1945, Zublin sidetracked a well with eight drainholes. He eventually re-entered about 250 vertical wells in California, West Texas, and Wyoming, with an average of two laterals.

First True Multilateral Well
The first true multilateral well, 66/45, drilled in 1953 by Alexander M. Grigoryan in the Ishimbainefti field at Bashkiria, now Bashkortostan, Russia. 

Grigoryan graduated as a petroleum engineer from the Azerbaijan Industrial Institute in 1939. Two years later, he drilled one of the world’s first directional wells, the Baku 1385, using only a downhole hydraulic mud motor to drill the entire well bore. This is the first time a turbodrill was used for drilling both vertical and deviated sections of a borehole. The significant increase in reservoir exposure over vertical wells resulted in a corresponding significant increase in production and led to many more successful horizontal wells in the USSR. Grigoryan’s success in drilling innovation led to his promotion to department head at the All-Union Scientific Research Institute for Drilling Technology (VNIIBT) in Moscow, where he developed a new sidetrack kick-off technique and a device for stabilizing and controlling curvature without deflectors.

In 1949, Grigoryan, expanding on the theoretical work of an American scientist, L. Yuren, proposed branched boreholes to increase production in the same way a tree root extends its exposure to the soil. He tested his theory in 1953 when he drilled Well 66/45 using only turbodrills without rotating drillstrings, cement bridges, or whipstocks. The well had nine branches, each extending 262.5 ft to 984 ft (80 m to 300 m).

From 1953 to 1980, 110 more multilateral wells were drilled in East Siberia, West Ukraine and near the Black Sea. Thirty of these wells were drilled by Grigoryan, who is recognized as the father of multilateral technology.

In the 1980s, Grigoryan moved to Los Angeles, Calif., and opened a company named Grigoryan Branched-Horizontal Wells. He was a member of the SPE L.A. Basin Section from 1997 until his death in December 2005 at the age of 91. Before his death, Grigoryan received recognition in 2003 as a Technology Pioneer by Offshore Energy Center’s Ocean Star Offshore Drilling Rig and Museum.

Thanks to the pioneering efforts of Grigoryan, Multilaterals began to take off in the United States in the 1980s. Arco drilled the K-142 dual lateral well in New Mexico in 1980, and UPRC drilled 1,000 multilaterals in the Austin Chalk from the 1980s to 1998.

Simple open-hole and cased-hole sidetracking to create multilaterals are known as Level 1 and Level 2, respectively. It was in the 1990s when “modern” multilaterals began as systems were built to create multilateral junctions that went beyond simply sidetracking a well and provided new capabilities. Modern multilateral systems fall into categories of Level 3 through Level 6, and significant milestones with these systems came in quick succession:

•   1993 – 1st Level 3 multilateral, Shell, Alberta, Canada.
•   1994 – 1st Level 4 multilateral, Shell, Alberta, Canada.
•   1995 – 1st Level 5 multilateral, BP, Gulf of Mexico, US.
•   1996 – 1st through-tubing multilateral intervention.
•   1997 – Technical Advancement of Multi-Laterals (TAML) formed.

With such growth in the number of multilateral systems, installations and well complexities, a Shell Expro engineer, Eric Diggins, decided to form an operators group to share worldwide multilateral experiences, establish an informal network of contacts, and provide a more unified direction for the development of multilateral technology. The  kick-off meeting was held in the Expro offices in Aberdeen, Scotland in March 1997. Participants included BP, Norsk Hydro, Statoil, Esso UK, Exxon, Mobil, Phillips, Maersk, Texaco, Total, Chevron, Shell Oil, Shell International E&P and Shell UK Expro.

One of the new group’s tasks was to create a Classification System for Multilaterals. The results were published in 1998 and included two tiers, a complexity ranking and a functionality classification. An example of this two-tier classification is: Level 6; N-4-IN-S-PR-RMC.  Level 6 refers to the complexity ranking. The string of letters and numbers that follow are the functionality classification: new well, four junctions, injector, single upper completion, re-entry by pulled completion, remote monitoring and control. In 2002, some minor changes were made to the complexity ranking definitions to accommodate new multilateral systems that had entered the market.

While the organization began as an operators’ forum, service companies were included in a portion of the face-to-face meetings. In 2001, a service company hosted a TAML meeting for the first time, and membership eventually became open to operators, service companies, and academia. The current membership has grown to 22 companies. With input from TAML and the continued effort of the service companies to provide improved tools, the evolution of multilateral technology has continued with additional milestones:

• 1998 – multilaterals started evolving toward intelligent wells.
• 1998 – 1st deepwater Level 5 from a floating rig, Petrobras, Brazil.
• 1999 – 1st Level 6, AERA Energy, California.
• 1999 – 1st intelligent multilateral, Level 2, BP, UK.
• 2002 – 1st multilateral system floated in, Level 3, Chevron, China.
• 2002 – 1st intelligent Level 6, CNOOC, Indonesia.

More than 50 years after that first multilateral by Grigoryan, the estimated number of multilateral junctions installed through the end of 2006 is estimated to be greater than 8,000. Level 1 and 2 multilaterals have become so common that those numbers are no longer tracked by the industry, and the actual number of installations could be as high as 10,000.

While all countries in which Level 1 and 2 installations cannot be determined, there are a minimum of 29 countries on six of the seven continents covered by the remaining levels.

Multilateral technology is neither new nor emerging, but even with global numbers in the thousands, it is still not considered mature by the industry. Multilaterals have not yet reached the acceptance level of horizontal wells, but with the economic incentives the technology offers in terms of reduced well count and equal or greater number of penetrations into the reservoir, it makes sense to evaluate projects for possible candidates, especially where horizontals are already being drilled. The challenges of sand control in and remote control and monitoring of each leg of a multilateral have been conquered. As for future multilateral milestones, the next big challenge is deepwater and ultra deepwater wells, where costs and risks are extraordinarily high.