The horizontal drilling techniques of today’s oil patch are the culmination of a long series of technological advances begun in the earliest days of the oil and gas industry. Originally, directional drilling—or sidetracking—using a variety of deflection drilling devices was developed to solve a number of problems associated with well drilling. In those very first days it involved deviating a well bore from the vertical to avoid some obstruction such as lost tools in the hole or possibly to straighten a crooked hole. As it grew more sophisticated it was used to create bottom hole completion points somewhat distant from the vertical in order to drill beneath a small town, to avoid having to set up operations in swampy areas, or to deal with some other similar situation. One of the most famous early specimens of this practice was the well known as the Petunia #1, which was drilled in Oklahoma City for completion beneath the state capitol building. Finally, in the more recent times, technological advance has allowed a truly horizontal drilling operation to take advantage of the various shale formations that once were deemed unfeasible, where production was concerned.
Beginning with the 69-foot Drake well near Titusville, Pa., in 1859 and continuing to the present 20,000-foot behemoths being drilled all over the world, the ability to drill a crooked hole on purpose has become more and more important. The first recorded instance of a planned directional drilling project occurred in South Africa sometime before 1912. The technique was not developed in the United States until 1933 in the Huntington Beach California Field, where drilling on land allowed wells to be produced from locations beneath the ocean. However, as far back as the early 1890s the practice of utilizing uncontrolled or undirected drilling deflection devices for sidetracking jobs was a common practice.
The tools for sidetracking to bypass lost objects in the hole required a set of fairly simple tools. But regardless of the tools utilized, it was necessary to cement the hole a distance from the problem impeding drilling for the gentle angle of the sidetracking to be able to miss the obstruction. The best known and most widely used of those tools was the whipstock.
The whipstock is a concave cylindrical device from eight to twelve feet in length that is tapered from top to bottom at a 1 3/4 degree to 2 1/4 degree angle. When set in the hole bottom, the thin edge of the top part of the device causes the drill bit to angle off and make the hole deviate from a vertical orientation—this being done in order to drill around whatever the downhole problem might be. In the very earliest days whipstocks were made of wood and were left in the hole for a permanent guide. Metal soon began to be used and when welding became a common practice whipstocks were often made on location by cutting a wedge shaped portion of casing, turning it upside down and placing it in the hole. Additionally, various kinds of attachments were invented to maintain the devices in place while being utilized.
Eventually whipstocks became factory-made devices of varying sizes, lengths, and tapers to be used for specific job applications. By the early 1930s removable whipstocks were developed with a strong collar at the top of the device of a diameter suitable for the drill bit to enter. It had been discovered that once the hole had been drilled approximately 15 feet beyond the whipstock, the device could be removed without the hole deviation being affected. Thus a set of whipstocks of varying sizes and tapers could be kept in stock and used over and over again.
Use of the knuckle joint to change drilling inclination was also developed in the early 1930s. A knuckle joint is essentially a pilot reamer with a flexible universal joint built in between the reamer and the drill pipe. The earliest devices were spring loaded in order to keep the reamer oriented to the direction it was originally set. After drilling approximately 20 feet the knuckle joint is removed and the hole checked for inclination and direction. If it is on target the device is reinserted for drilling another 20 or so feet, after which a regular bit is utilized to resume the regular drilling operation.
A third deflection method of hole deviation drilling used in the early days was the use of spudding bits. They are simply shovel shaped bits that tend to dig to one side of a hole. For purposes of sidetracking they were normally used in softer formations to create about a four-foot depression on one side of the hole. It was then removed and the regular drill bit was carefully lowered into position with the hope that it would slide into the cavity created by the spud bit. By turning the drill pipe slowly and using minimal mud pressure the method usually resulted in a changing of the inclination of the hole.
The use of deflecting tools was by no means the only way to change the direction that a well bore took. There are a variety of drilling techniques available to maintain the desired orientation of a well bore. Among those are the weight on the bit, changing rotation speed, mud pressure and composition, and the use of special bits, to name a few. Maintaining the desired orientation of a well is a complicated situation to say the least and along with it a variety of measuring devices were developed to verify the change in well inclination and direction.
Then in 1957 a new technique of changing well inclination developed that did not require the use of deflecting tools. It was known at the time as “badger jet drilling” and was effective in softer formations. The way it worked was for a three-cone bit, modified so that it had one large mud jet and two smaller mud jets, be lowered into the hole with a deflector shielding the smaller jets. The bit was oriented so that the large jet pointed in the direction of the deviation and the mud pressure applied along with a great deal of weight without the drill pipe turning. Every few minutes the pipe was raised to allow the cuttings to wash out and the technique once again applied. After about seven to ten degrees of inclination was accomplished, regular drill pipe was inserted and drilling resumed.
By the 1970s the use of downhole drilling motors (aka mud motors) was developed. They work by using the hydraulic pressure of drilling mud on a series of vanes to rotate the cones on the drill bits so that it is not necessary to rotate the drill pipe to get the cutting activity of the cones. All that is necessary is to maintain the weight necessary to force the bit through the formation being drilled. This also allows the direction of the drilling to be controlled by various adjustments to mud pressure, weight application, cone rotation speed, and others.
Regardless of the mechanical sophistication of the equipment used, it serves a limited useful purpose if it is not planned and controlled. In those earliest efforts at deflection of well bores the actual end location of the hole was not of particular importance as long as the avoidance of the hole obstruction was accomplished. However, when completing a well beneath a town, or a lake, or some other similar situation, being able to predict where the well would bottom out became of considerable importance. In the 1930s the slant hole drilling, as it had come to be called, fell into considerable disrepute when a number of wells in East Texas were drilled to completion under neighboring leases and numerous lawsuits were brought for stealing oil through the use of slant hole drilling. For many years those outside the oil and gas business viewed the term slant hole drilling as some sort of illegal practice and had little knowledge or understanding of its importance to the industry.
The combination of more efficient equipment for drilling off vertical oil wells and the technology to determine where the drill bit was located beneath the surface resulted in one of the most spectacular rejuvenations of the oil and gas industry in its history. It took place in the Barnett shale play in North Texas in the general Fort Worth area. In 1981 George Mitchell began trying to find a way to bring that dying oilfield country back by producing the Barnett shale that underlay vast parts of the area. The Barnett was a tight formation that had resisted numerous attemts to produce it. It took Mitchell years of constant experimentation and untold amounts of money utilizing known technology of directional drilling in order to drill the formation horizontally and then perfect a technique of frac’ing such a tight formation until finally in the mid-1990s after a 15-year effort he solved the problem, brought that area back into significant production, and allowed a host of oilmen across Texas and the nation to open up oil and gas fields in hitherto unknown territory.
So it was that, as with much of today’s oilfield technology, it all began with simple home-made devices meant to solve immediate problems and evolved into sophisticated systems that those in the early days of the industry could not have dreamed of in their wildest imaginings. There is no doubt in my mind that there is some poor soul out there struggling with one of the myriad of difficulties surrounding the drilling and production of oil and gas who is at this very moment in the process of creating similar problem solving devices.
Bobby Weaver is a regular contributor to Permian Basin Oil and Gas Magazine. His monthly humor column, “Oil Patch Tales,” appears in each issue. Subscribe today.