Drilling

Drilling an oil well is an expensive proposition. It requires large, complex machinery, a skilled workforce and lots of time. When drilling for oil began in Turner Valley in 1913, the standard piece of drilling equipment was the cable tool rig. By the mid-1920s, rotary rigs were also in use and gradually becoming more prevalent.

A. W. Dingman and W. S. Herron were the first to drill for oil in Turner Valley. After raising sufficient capital, Dingman brought in a cable tool drill from California, and Herron built a derrick near the gas seep he had found on the bank of Sheep River. Drilling commenced on January 25, 1913. Their rig was typical of the period. Above a large pit called a cellar, the wooden drilling rig rose to about 25 m (82 ft.) in height. The pyramid-shaped derrick tapered to only 1.5 m square (5 ft.) at the top. Here, pulleys known as the crown block were mounted to support cables for raising and lowering the drill, bailer and well casings.

A cable tool rig bored a hole in the ground by repeatedly raising and dropping a heavy bit suspended from a cable. The bit was very large and when combined with the other components of the cable tool string was several meters long and could weigh over 1,800 kg (4,000 lbs). Thus, a powerful engine was required to run such a rig. At frequent intervals—about every metre (3 ft.) of depth—the bit was removed from the hole, and the slurry of water and pulverized rock at the bottom of the hole was removed using a bailer. The bit was then re-inserted, and drilling recommenced. When a bit became dull, it was removed from the string and “dressed,” or sharpened. Several bits were kept on hand so that work could continue uninterrupted. As the hole got deeper, it was lined with pipe, called casing, to prevent the sides from caving in. The process of drilling, bailing and casing became ever more laborious and time-consuming as the work progressed.

Perpendicular to the derrick was a long enclosed shelter, called the drill shack, that housed the machinery to run the rig. Farthest from the well was a steam engine—initially coal-fired—that provided all the power to move the various cables. A long belt running from the engine turned a crank, moving one end of a walking beam—essentially a huge teeter-totter—up and down. This motion lifted and dropped the cable tool drill at the other end of the walking beam. The first drill bit used at Dingman No. 1 was 50.8 cm in diameter (20 in.). As the hole got deeper, smaller diameter bits were used.

Incredibly, Dingman’s first Turner Valley well was successful. At a depth of 142 m (467 ft.), a sufficient supply of gas was encountered to replace the coal that fuelled the steam engine powering the rig. After more than fifteen months of drilling, Dingman No. 1 came in on May 14, 1914, at a depth of 828 m (2,718 ft.). Eleven days after the drilling of Dingman No. 1 was complete, a second well—Dingman No. 2, Alberta’s first steel drilling rig—was sunk nearby to capitalize on the find.

A cable tool rig was also used to drill the Royalite No. 4 well, which hit wet gas on October 4, 1924 at 1,140 m (3,750 ft.). An incredible volume of gas—close to 595,000 cubic metres (21,000,000 cubic feet) per day—as well as naphtha, spewed from the hole, shooting the casing as high as the crown block at the top of the derrick. The wooden rig became soaked and went up in flames when the well caught fire. Though the fire was put out after several days, the well caught fire two more times before it was finally extinguished for good and the flow brought under control in December. Despite the fire, it was noted in 1930 that Royalite No. 4 was “…the first well to give production adequate to compensate for the unusually high drilling costs experienced in the valley, because of the hardness of the rock which has to be penetrated and because of the slanting formation which enjoins extreme care if crooked holes are to be avoided.” Royalite No. 4, the “…famous million dollar well,” remained productive for many years.

The need to drill deeper resulted in further changes to the drilling equipment. Lighting was added to the rig so that drilling could continue through the night. Derricks became larger and heavier, and the boilers bigger. Steel cable also replaced rope when steel rigs became common.

Another innovation was the rotary drill. Rather than pounding its way into the ground, like a cable tool rig, the rotary drill used a spinning motion to grind away at the ground. Although the rigs looked similar from a distance, they operated very differently. The rotary drill had a mechanism that caused the entire drill stem to spin. As the depth of the well increased, lengths of pipe were added to the drill stem. Changing a drill bit necessitated removing the entire drill stem—called “tripping out”—a laborious process of hauling up, unscrewing and stacking many lengths of pipe. Of course, then it was necessary to put it all back down the hole—called “tripping in”—

in order to continue drilling. Despite the fact that rotary drills required a larger crew, they were usually much faster that cable tool rigs, making them a cost-effective alternative.

In 1925, Royalite brought in two rotary drilling rigs, which were used to drill the Royalite No. 5 and No. 6 wells. Rotary rigs encountered some difficulties because of the hardness of the ground in Turner Valley, but modifications were made and, by 1929, both cable and rotary rigs were in equal use. By the late 1930s, however, rotary drilling had become the preferred method. Initially, steam engines were used to power rotary drilling rigs, but by the late 1940s these had been replaced by diesel. Significant power was required to turn the drill stem consisting of thousands of feet of pipe in the bore hole, with the drill bit at the end. The weight of 15 cm (6 in.) diameter pipe in a 1.5 km (5,000 ft.) deep hole is about 68 tonnes (150,000 lbs.).

Another departure from cable tool rigs was the use of drilling mud with rotary drills. While the name “mud” might suggest a rather insignificant substance, it actually has an important role to play in maintaining the optimal environment for the drill bit. Pumps circulate the drilling mud continuously from the surface to the bottom of the hole and back. Frequent analysis of the returned mud reveals what sort of material is being drilled and allows for adjustments to be made for its composition and consistency.

For reasons of safety and durability, steel rigs became standard in the 1930s. Some metal derricks were placed on skids, so they could be moved from one drilling site to the next. Later, portable rigs and rigs that could be broken down into sections were also developed.

Drilling activity peaked in Turner Valley in 1930, when fifty-six wells were sunk. Over time, the average depth of wells increased, especially after oil was discovered at the south end of Turner Valley in 1936 at a depth of 2,080 m (6,828 ft.). This was the confusingly-named Turner Valley Royalties No. 1 well—not affiliated with Royalite—which changed the focus of activity in the area to deep drilling for oil. As oil and gas were removed from the ground, pressure in the field diminished, and additional measures, such as pumping in water or detonating explosive charges down the hole, were used to promote flow. The last well drilled in Turner Valley was completed in 1950.