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Bolivia, 1924

Any wish to understand the early history of oil and natural gas exploration throughout the world must embrace the intricacies, and ingenuity, of cable tool drilling.

Rotary drilling came into play by 1902-1906 in Southeastern Texas and was in full swing in most places in America by 1915, but cable tool drilling was critical to many worldwide discoveries all the way into the mid 1930's. A good bit of that had to do with the "convenience" of percussion drilling in remote, hard to access parts of the world, like Southeastern Bolivia, seen in this series of amazing photographs of Standard Oil of New Jersey in the early 1920's.

Bolivia's exploration efforts were focused on rugged terrain on the eastern slope of the Andes Mountains. Nothing was easy about building locations and moving rigs.

The photograph, on the left is a rig build out underway.

The massive band wheel [1] is set on this cable tool rig and the Pitman arm is laid down. Note the substructure is a combination of hewn beams and simple logs. Workers are aligning the Samson post before setting the walking beam and, eventually, attaching the Pitman arm to that walking beam. The band wheel goes round and round, the walking beam goes up and down.

The main draw works drum (bull wheel) has not been spooled yet with rope, nor have sand line drums in the foreground. I like to think of these auxiliary drums as precursors to cat heads and/or what we call on modern rigs, air "tuggers." They contained rope, also, that were used for bailer trips to clean the well out and pickup lines, all of which will eventually be strung under calf wheels [1] then over the crown on this small, angle iron, standard derrick.

Typical "portable" steam boiler for powering cable tool rigs.

Wooden derricks, substructures and floors were easily crafted from local lumber sources and the main power source for cable tool rigs was, of course, steam. Steam boilers were fairly easily built and moved via mule trains, etc.; fuel sources like coal, or wood were readily available, as was water. Casing was required in cable tool drilling, but not drill pipe, nor mud or mud pumps, and bailing pulverized rocks, or shales, was a good analytical tool to the driller recording what he was drilling in the subsurface.

Casing likely in inventory in Standards camp in Bolivia. Various sizes are indicative of a probable casing program for a single well.

Cable tool drilling generally required the running of several concentric casing strings, from large to small, as the well progressed to deeper debts. This provided hole stability, prevented sloughing, offered some blowout protection thru containment and casing strings, more often than not, acted as production strings once the well came in, or was "enticed to come in with torpedo shots of glycerin.

In unstable hole conditions it was sometimes necessary to drive, or force casing strings down hole, so well bores had to be straight and not deviated much from true vertical. A great deal of care was used in setting conductor pipe at the surface because that was the beginning of keeping the well bore vertical. Drillers would level the rig with shims, etc. and cross string lines into an X over the hand dug cellar to make sure the start of the drilling was true to absolute vertical. Mama nature assisted in the percussion drilling process with the help of gravity; the best way to pick up, and drop, your down hole bit as straight as possible was to make the entire bottom hole assembly as heavy as hell.

Bit and BHA during a pre-spud meeting.

Based on the photograph of the bottom hole assembly hung in the derrick, above, this well in Bolivia is about to be spud and the bit is large enough to be able to dig a hole large enough to drive + 13 inch OD conductor pipe, or surface pipe, as deep as 300-400 feet. This big bit, X-over subs to weighted "drill collars" and even a set of mechanical jars (if the assembly got stuck), weighed a ton and a half or more [2]. At pickup, the driller would actually place a hand level on his hemp drill line to check for vertical deviation, it was that important to drive the first string of casing that straight.

Please note the size of the wrenches used to make the bottom hole assembly up! That's some big iron to be man-handling. These assemblies were made up by hand, then tightened with snatch blocks and cat lines from the sand line drums powered from the boiler(s) to the main band wheel.

Smaller bits and bottom hole assemblies then allowed the next casing settings to be set as straight as possible. Most old cable tool drilled wells might have as many as three strings of casing in them before TD was reached, a 13 3/8ths conductor, down to 10 inch, then down to 8 inch OD. The slightest little hint of hydrocarbons in a bailer trip to clean out the hole was a sign to set a protective casing string.

The first string of casing is set in the photo, above. Below the rig floor is a sort of drilling spool, or T-assembly in the cellar (with a full opening valve, I hope) and on that is bell nipple, flared at the top, and brought up to the height of the rig floor. The driller has his hand on what is called the "temper screw" and is making hole...the slow, arduous process of the walking beam moving up and down, dropping and raising the bottom hole bit that pulverizes rock and shale. Bailer trips cleaned the hole out and the process was repeated. Drilling a 2,000 foot well could often take several months.

Standard Oil drilled 24 wells in SE Bolivia in the 1920's and 30's, with marginal success. They abandoned Bolivia but not before stirring up trouble between that country and Paraguay over exaggerated oil potential in the region. Over 1oo,000 men from both countries were killed in the ensuing war. Standard provided fuel in the war effort, to both sides. Ultimately very little oil was found in the area of dispute.

The next time we write about cable tool stuff on Oily Stuff we'll talk about temper screws.

Viva Bolivia !


These photographs are of Standard Oil of New Jersey's initial exploration efforts in Southeastern Bolivia in the early 1920's and are provided by Dr. Miguel Tinker Salas, PhD and renown Latin America Historian at Pomona College in California.


[1] Cable tool basics

[2] Bit and BHA


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