Every Way

But Up

A Look at Modern Directional Drilling

Scott Cunningham

EVERY WAY BUT UP 2

Every Way But Up:

A Look at Modern Directional Drilling It is a fair assumption that most people are familiar with the basic concept of drilling: A drill is directed downward into the surface and pressure is applied, thereby causing the drill to move through the ground. This continues until the drill has reached it target. However, many people are probably unfamiliar with the process of directional drilling. Although the name may sound self-explanatory, there is much more to this technique than it would first seem. This paper aims to explain and explore the processes of directional drilling.

Directional Drilling The process of directional drilling is, at its base, just drilling in a non-vertical direction. In fact, this is exactly what the very first practitioners of directional drilling did. “Slanted oil wells…drilled by experts who use special tools and secret methods to send the bit burrowing into the ground at strange angles” (Gleason, 1934). Today, producers utilize modern technology so the process has much more to it than just drilling non-vertically. For instance, the drill head has to be tracked and steered so that it will end up at its intended destination (something vertical drillers have no need for as they only need to let gravity do its job). As such, this paper focuses on the more modern styles of directional drilling, such as wells shown in Figure 2, horizontal wells (an extension of directional wells—more on this in Methodology) and surface horizontal and directional drilling (HDD). This paper looks at some of these modern technologies, but also the methodology and the applications of directional drilling.

Tools for the Trade This section examines some of the integral components in the drilling process individually, while explaining how they aid in the overall drilling process. The three components included are: the drilling rig, the drill, and the drill tracking system. Each of these components is part of what makes directional drilling possible.

Figure 1: A graphic depicting directional wells as implemented in 1934.

Source: Popular Science, May 1934

EVERY WAY BUT UP 3

The Drilling Rig Since the drill naturally goes downward (even if not straight vertically), it makes sense to start at the top when talking about drilling. That’s what a drilling rig is: the top of the drill. There are two types of drilling rigs that are involved in when someone doesn’t want to drill straight down. Both operate on the same basic idea, turning the drill string to turn the drill. Though, as we will see later, this isn't always the case.

First there are the rigs used when drilling directional/horizontal wells. These rigs are the standard drilling rig (Figure 3) used in almost every drilling operation regardless of direction. This rig works by using an engine to rotate the turntable, which transfers its momentum to the drill string, thereby turning the drill at the end. The second type of rig is used for surface HDD. These rigs are much smaller, because they are typically used for shorter distances at a time, as opposed to a standard rig, which may drill for much longer periods. These HDD rigs come in 3 sizes: Mini, Midi and Maxi. All three sizes operate the same way, with the size determining only the power level of the machine. The motor turns the drill string, while the chain drive provides the force behind

the drill that is necessary for forward movement. Figure 4 shows the basic setup of one of these HDD machines. These types of machines can use the same drill the whole time since they begin by drilling directionally.

Figure 2: A collection of directional wells. Source: Mackenzie Gas Project, Retrieved 2016.

Figure 4: A simple diagram of the standard oil drilling rig. Source: Amerex Coropration, Retrieved 2016.

Figure 3: A basic HDD rig. Source: Willoughby, 2005. Chapter 3.1

EVERY WAY BUT UP 4

The Drill Itself The most obvious difference between a directional drill and a standard (vertical) drill is that a directional drill needs to be able to drill not only straight, but also at a slight angle. The methods for this directional control range from simple to complex. I will take a brief look at two methods, one simpler and one more advanced. Let’s take a look at the simple method first. On these drills, there is a drill motor (a.k.a. “mud” motor) placed behind the drill bit which is turned by the force of the drilling fluid (a.k.a. “mud”) that is pumped down the drill pipe. This means that the drill string is actually not turning. The motor is bent at a certain angle, and remains fixed while drilling the hole in the direction of the bend (Hart, 2008). Figure 5 below shows the typical setup in one of these motors. Notice the placement of the drill motor behind the drill bit on the left. You can see that the pink “mud” passes directly though the motor on its way to the nozzle in the drill bit. Hart continues to point out that despite appearing straight, the motor is actually bent at approximately a two degree angle. He also notes that these motors are usually adjustable as well, allowing operators to change the angle if needed (2008).

The more complex method is known as a Rotary Steering System (RSS). These drills more closely resemble the traditional straight line drill because unlike the drill motor types, they continue to use the drill string as power for the drill bit. In contrast to a standard drill, these drills don’t have to stay straight. They have some mechanism, usually controlled by means of a proprietary program, which allows the operator to angle the drill in real-time. For example, the drill bit in the Halliburton Geo-Pilot ® RSS © (Figure 6) is directed by the internal drive shaft which is itself adjusted by a pair of offset rings (top-left). This system can produce up to six degree deviations per 30m (right), all while continuously drilling (Halliburton, 2012). These are two common types of directional drills. Although the end result is similar, they have distinct differences in their operation. Both types can be used for either directional wells or HDD.

Figure 5: Cross-section of a "mud" motor drill. Source: energyindustryphotos.com, Retrieved 2016.

Figure 6: The Halliburton Geo-Pilot ® RSS © drill.

Source: Halliburton, 2012.

EVERY WAY BUT UP 5

Systems for Tracking the Drill There are two main systems in place for keeping track of the drill once it is underground. These two systems are the walkover system and the wire-line system. The walkover system is used exclusively in HDD projects, whereas wire-line can be used in either directional or HDD projects. However, there are also some newer technologies that can be used to track drills as well. The walkover system involves, as its name suggests, involves physically walking over the drill. The drill has a sonde (a type of transmitter) attached near the drill head which depth and position. This transmitter then sends the information to a receiver being carried along by the person walking above it, and optionally to a receiver at the drill rig. Modern receivers can be used for depths up to 140 feet. (Willoughby, 2005, Ch. 8.1.1). This makes it easy to see why it would be difficult to use in oil-gas directional drilling, where the drill is deep beneath the surface. However, as modern wireless technology has advanced, so too has the walkover system technology. These days, workers are able to utilize more accurate locating systems and the ability to draw the drill path in real time (Kezdi, 2015).

On the contrary, wire-line systems involve sending the data through a wire connected from the sonde back up to the operator. The data collected in this method is typically forward motion, horizontal azimuth and vertical azimuth. (Azimuth is the direction of the drill relative to north.) This data is then used to calculate the drill’s location (Withers, 2012, p. 26). These systems sometimes require the wire to be magnetized, as some of the instruments in the sonde may utilize magnetic technology which is easily disrupted by the Earth’s natural magnetic fields (A.E. Yates Co., n.d.). More technologically advanced drills, such as the Geo-Pilot ® pictured above have wire-line technology built into the mechanism for directing the drill.

Figure 8: Illustration of the Walkover Process.

Source: Willoughby, 2005, Ch. 8.1.1

Figure 7: Typical Setup of a Wire-Line System. Source: Dorffer & Rose, 2015.

EVERY WAY BUT UP 6

Two of the newer technologies for tracking a drill are both nuclear based. The nuclear technology falls into two categories: neutron/gamma detection and nuclear magnetic resonance (NMR). Both technologies work by measuring what is known as the Hydrogen Index (HI), which is defined as “the amount of hydrogen per unit volume of formation” with the HI of freshwater being 1 (Kennedy, 2015, p. 118). These technologies focus less on knowing exactly where the drill is (although this is still monitored for obvious reasons) and focus more on knowing what is around the drill by examining the substrate. By knowing what surrounds the drill, the operator can more effectively navigate underground. During preliminary testing done in 2008 for neutron/gamma detection systems, researchers attempted to use a radiation source and receivers to indentify materials surrounding the apparatus. This testing indicated that “(1) other objects may not be detected and (2) these methods are unlikely to be able to distinguish objects of interest from the clutter of natural variations and objects in the ground” (Hilton et al., 2008, p. 22). However, since science and technology are always advancing, this type of system has become more reliable in more recent years. For instance, only three years later Reijonen claims, “Nuclear well logging is an integral part of modern well logging operations.” The HI measurement allows the operator to determine the porosity of the formation. Then, the thermal neutron capture cross-section can be used to identify the presence of hydrocarbons, as well as the elemental composition in the formation (Reijonen, 2011, p. 434).

Nuclear magnetic resonance works by creating a small magnetic field around the apparatus. Hydrogen atoms within the field align themselves with the field. When the field is removed, the hydrogen atoms return to their original position. Since the magnets are permanent, the field cannot actually be removed. Instead, another component outputs electromagnetic radiation, which amplifies the field when it is turned on. The time it takes for the atoms to return to normal after turning off the secondary component is what is measured. This is known as the T2 distribution (Kennedy, 2015, p. 130). The time can be used to

distinguish materials in the formation because “[t]he hydrogen atoms that are relatively free to move, lose their alignment relatively slowly…whereas hydrogen atoms that are in environments where movement is restricted lose their magnetisation much faster” (Kennedy, 2015, p. 130). Essentially, the tool is determining the HI, but in a much different way. Hydrocarbons can be identified by their HI values ( < 1) and extended T2 distributions. Often, the data is cross referenced with other density measurements to confirm the presence of oil and/or gas (Blanz, Kruspe, Thern, & Kurz, 2010).

Figure 9: Diagram of a neutron/gamma detector system. The neutron source emits neutrons which move into the

surrounding earth. The detectors pick up the neutrons/gamma rays when they have slowed down

enough. Source: Reijonen, 2011.

EVERY WAY BUT UP 7

Each of these individual components plays an important part in the drilling process. There’s the rig which is the entry point and surface power source for the drill (when applicable). Then, there is the drill itself, which is arguably the most important piece of directional drilling equipment because it allows the directional part to happen. Finally, there is the drill sensor, which allows the operator to keep track of the drill.

Methodology The actual process of directional drilling can be simplified to relatively few steps. The process is slightly different depending on whether directional (and horizontal) wells are being made or HDD is being performed. The difference lies in how the hole is drilled. For example, in both methods “mud” is used to help the drill get through the ground and remove drilled debris from the hole. Both methods also utilize a casing system in the well to fortify the sides and prevent collapse. Mentioning these similarities here is sufficient enough discussion that they will not be included in each individual section. First, let’s look at directional wells. The well begins as either a typical vertical well (Figures 11, 12) with the intent of veering off later or as a directional well (Figure 2), drilled by a standard drill rig. If the well begins as usual, then the well is drilled to a certain point, known as the kickoff point (Figure 11), before beginning to change direction. Some companies will use a standard vertical drill until the kickoff point and switch to the ”mud” motor drill when beginning the directional portion, while others simply use their RSS drill on its straight setting. Using the directional drill, the well is drilled until its terminus. If the well begins at an angle initially, the company may use either a standard drill (if going in a straight line) or a directional drill if they intend the well to have a curvature. Again, they drill until the terminus.

Figure 10: Depiction of a NMR device. Source: Blanz et al., 2010.

Figure 11 (above): An assortment of directional wells. Source: Oil & Gas Videos, formerly

bpglobal.blogspot.com. Retrieved 2016.

Figure 12 (right): A directional well showing the kickoff point. Source: Inglis, 1987.

EVERY WAY BUT UP 8

A horizontal well is a specific type of directional well. The U.S. Energy Information Administration defines a horizontal well as “a well that begins as a vertical or inclined linear bore which extends from the surface to a…’kickoff point,’ then bears off on an arc…and, thereafter, continues at a near-horizontal attitude tangent to the arc” (1993, p. 1). A typical arc has a radius of 300-500 feet (Helms, 2008, p. 1). The process for a horizontal well follows the steps above for a directional well. Both horizontal and directional wells can use wire-line or one of nuclear tracking systems, although horizontal wells tend to use the more high-end nuclear ones as they are generally better for staying closer to horizontal. Horizontal directional drilling (HDD) is performed using the second drilling rig discussed above, because the operations generally require less power. These operations begin drilling at very shallow angles (see Figure 13). Willoughby, 2005 suggests that “[t]he entrance angle of the drill string should be between 8 and 20 degrees, with 12 degrees considered optimal” (Ch. 5.4.5). This shallow angle is intended to allow the drill to exit the other side with relative ease. Because the drill is generally not very deep and the curvature not very severe, a “mud” motor drill is usually used. The primary location system used is the walkover method, unless the drill is done in an area which makes this impossible (such as under a river like in Figure 13), or the borehole is unusually long or deep. In these cases where walkover is impossible, the wire-line method is usually used (Willoughby, 2005, Ch. 8.1.2).

Applications In this section, the common applications of the three types of directional drilling previously discussed are examined. Note that these are not all the applications, just the most common ones. Directional drilling is, according to Inglis, most commonly used for sidetracking, avoiding geological problems, and reaching underneath inaccessible locations (1987, p. 5). Sidetracking is primarily implemented in three situations: when the borehole becomes blocked for whatever reason

and must be circumnavigated, when a borehole misses its mark, and if the current zone of the reservoir has been depleted (Inglis, 1987, p. 5-6). In all three situations, sidetracking is performed the same way. The section of borehole to be sidetracked is blocked off with concrete. The deepest empty point is now treated as the kickoff point, and drilled as described above. The two other uses for directional drilling are related. Basically all they mean is that you drill directionally to reach somewhere you can’t access by drilling straight down, such as under mountains or a town.

Figure 13: Example of a HDD operation. Note the small entry angle and relatively shallow depth of the drill.

Source: directionalboringcentral.com, Retrieved 2016.

EVERY WAY BUT UP 9

“Most oil and gas reservoirs are much more extensive in their horizontal (areal) dimensions than in their vertical (thickness) dimension” (U.S. Energy Information Administration, 1993). This statement exemplifies the reason horizontal wells are most commonly drilled: to expose more of the formation to the borehole’s surface than a traditional vertical hole. This allows for greater extraction volume from one initial vertical borehole. A quick glance at Figure 15 makes it clear that a horizontal well will have much greater exposure than a vertical well. An examination of Figure 16 reveals a direction correlation between the number of horizontal wells and the cubic feet of gas produced over 6 years in Pennsylvania.

HDD is used in the petroleum industry for installing pipelines. The low angle drilling is ideal for installing pipelines beneath the ground. The fact that the drill comes out at some point is helpful for connecting parts of the pipeline because it provides a good way to mark intervals for the pipe. Parts of the Keystone pipeline were built using HDD techniques according to Bonham (2007). Obviously if such a large-scale pipeline can be built this way, it is even more feasible for smaller operations. The applications discussed are only some of the ways these processes can be used. I have only presented here a snapshot of the landscape which is petroleum engineering.

Figure 14: Illustration of sidetracking procedure. Source: Inglis, 1987.

Figure 15: Graphs showing the relationship between horizontal well count and natural gas production. Source: U.S. Energy

Information Administration, 2012.

Figure 16: Comparison between horizontal and vertical well borehole surface exposure. Source: U.S. Energy Information

Administration, 1993.

EVERY WAY BUT UP 10

This paper has taken a glimpse into the world of directional drilling. Some of the technologies used in both directional/horizontal wells and horizontal directional drilling (HDD) were looked at on a basic level. These technologies were the two different drilling rigs used in each of these operations, two types of drills used for drilling non-vertically, and four methods for tracking the drill underground: walkover, wire-line, neutron/gamma sensing, and nuclear magnetic resonance. During the discussions of these technologies, comments were made in an attempt to aid in the explanation of the methodology for directional drilling. The methodology was then expounded upon for each of directional wells, horizontal wells, and HDD operations. Some common real-world applications for each of these processes were discussed, with support from multiple sources attesting to their use.

EVERY WAY BUT UP 11

References A.E. Yates Co. (2011). Horizontal Directional Drilling. Retrieved from

http://www.aeyates.co.uk/a-e-yates-trenchless-solutions/horizontal-directional-drilling

Site from a HDD company with basic information on the topic. Since they are a company in the industry, I think the information is okay.

Amerex Corporation. (2013). Oil and Gas 101: Oil well diagram. Retrieved from http://www.amerexco.com/Diagram.html

Sub-site from Amerex which is a simple look at oil/gas drilling. Only used for image.

Blanz, M., Kruspe, T., Thern, H.F., & Kurz, G.A. (2010). Nuclear magnetic resonance logging while drilling (NMR-LWD): From an experiment to a day-to-day service for the oil industry. Diffusion Fundamentals, 14. Retrieved from http://www.uni-leipzig.de/diffusion/index.html

A scholarly article specifically on NMR technology. Very helpful for the NMR section

Bonham, K. (2007, December 28). Drilling horizontal. McClatchy - Tribune Business News. Accessed from http://search.proquest.com/docview/462910874?accountid=13360

News article discussing HDD usage for installing Keystone Pipeline. Directional Boring Central. (n.d.) The directional boring advantage. Retrieved from

http://www.directionalboringcentral.com/library/dba/dbapamphlet.htm A sort of hub site for things related to directional boring (drilling). Only used for

image. Dorffer, D.F. & Rose, L.C. (2015). Patent No. US 8969728 B2 Washington, DC: U.S.

Patent and Trademark Office. Patent containing an image used in the paper. Energy Information Association. (1993). Drilling sideways -- A review of horizontal well

technology and its domestic application. Washington DC: Department of Energy. An official publication from the EIA on horizontal wells. Good source of

information. Energy Information Association. (2012). Horizontal drilling boosts Pennsylvania’s

natural gas production. Retrieved from http://www.eia.gov/todayinenergy/detail.cfm?id=6390

Report from EIA used to support argument that horizontal wells increase production.

“Geo-Pilot® Rotary Steerable System from Halliburton,” 2m 15s. [video] (2012). Halliburton Co. [producer and director]. Retrieved from http://www.halliburton.com/public/ss/contents/Multimedia/web/Geo-Pilot.wmv

Video from directly from Halliburton explaining the features of their product. Gleason, S. (1934, May). Slanted oil wells work new marvels. Popular Science Monthly,

124(5), 40-50. An article from an old magazine which concerns directional drilling.

EVERY WAY BUT UP 12

Hart, N. (2008). Horizontal drilling techniques, directional drilling methods. Retrieved from http://www.energyindustryphotos.com/horizontal_drilling_methods.htm

This is a personal website from someone who has been in the industry for over 25 years, so I believe the information to be credible.

Helms, L. (2008). Horizontal drilling. North Dakota Department of Mineral Resources Newsletter, 35(1), 1-3.

This is a low-level look at the process of horizontal drilling. Good for helping me understand the process.

Hilton, N.R., Archer, D., Brennan, J.S., Estrada, J., Lund, J.C., & Salmi, A. (2009). Feasibility of nuclear sensing for horizontal directional drilling. U.S. Department of Energy. doi:10.2172/1130399

Government sponsored study into nuclear sensing technology. Inglis, T. A. (1987). Petroleum engineering and development studies (book 2):

Directional drilling. Norwell, MA: Graham & Trotman, Inc. This is a very in-depth book on the entire process of directional drilling, was

useful via searching within the text for what I was looking for. Kennedy, M. (2015). Logs part II: Porosity, resistivity and other tools, In Practical

petrophysics : Developments in petroleum science (Chapter 5) (62), 107-149. http://dx.doi.org/10.1016/B978-0-444-63270-8.00005-0.

A very recent book on some topics of Petroleum Science. Specifically used for information on nuclear technologies.

Kezdi, M. (2015). Directional drilling: HDD locating systems improve as-built data. Trenchless Technology. Retrieved from http://trenchlessonline.com/directional-drilling-improving-underground-information/

News article from a site which contains a myriad of data relating to HDD. Looking into the site, I found it to be reputable.

Mackenzie Gas Project. (2007). Project description. Retrieved from http://www.mackenziegasproject.com/theProject/projectDescription/naturalGasFields/index.html

Site describing the Mackenzie Gas Pipeline project. Only used in paper for image. Oil & Gas Videos. (2012). Directional drilling objectives & profile line drawing –

Introduction. Retrieved from http://www.oilvips.com/2012/10/directional-drilling-objectives-profile.html

Site containing information on various oil/gas topics. Only used for image. Reijonen, J. (2011). Nuclear Tools For Oilfield Logging-While-Drilling Applications. AIP

Conference Proceedings, 1336(1), 433-436. doi:10.1063/1.3586136 This is a brief discussion on nuclear technology in the drilling field from an

American Institute of Physics conference. Willoughby, D.A. (2005). Horizontal directional drilling: Utility and pipeline applications.

(McGraw-Hill civil engineering series). New York, NY: McGraw-Hill. A textbook regarding HDD. I focused more on the pipeline sections. Withers, J. (2012). Rig size: Maxi vs. midi vs. mini. Horizontal Directional Drilling Guide,

1, 24-28. Magazine supplement produced by Trenchless Technology, who I have

determined to be a reputable source for topics in this field.

EVERY WAY BUT UP 13

Additional Consulted References1 Amerex Co. (n.d.). Oil and gas 101: Directional drilling. Retrieved from

http://www.amerexco.com/DirectionalDrilling.html Again, used to help learn about the process. “Directional Boring” Wikipedia entry. [Updated 25 January 2016]. Retrieved from

https://en.wikipedia.org/wiki/Directional_boring Used to learn and explore their references. “Directional Drilling” Wikipedia entry. [Updated 2 February 2016]. Retrieved from

https://en.wikipedia.org/wiki/Directional_drilling Used to learn and explore their references. Horizontal Technology Inc. (2013). Horizontal Directional Drilling / Boring (HDD): How

the Drill Bit is Steered. Accessed on https://www.youtube.com/watch?v=cl8BBoCV7gU

Used to see the mud motor in action and hear a simple explanation of its workings.

“Oil Well Drilling Process with animation” (uploaded 2015) Retrieved from https://www.youtube.com/watch?v=XhWrVx08j3M

Used to learn about rig operation. Questerre Energy. (2010). Shale Gas- Hydraulic Fracturing. Accessed on

https://www.youtube.com/watch?v=CM8Lh7SAm6A Although on fracking, there is a nice animation of a horizontal well being drilled. Rigzone. (n.d.). How does directional drilling dork? Retrieved from

http://www.rigzone.com/training/insight.asp?insight_id=295&c_id=1 Used to help learn about the process of directional drilling. Stoner Engineering, LLC. Glossary of terms. http://www.makinhole.com/glossary.htm Used to look up terms I didn’t know.

1 These additional consulted references have no corresponding Appendix entry because they are not

cited anywhere in the paper.

EVERY WAY BUT UP 14

Appendix

EVERY WAY BUT UP 15

EVERY WAY BUT UP 16

EVERY WAY BUT UP 17

EVERY WAY BUT UP 18

EVERY WAY BUT UP 19

EVERY WAY BUT UP 20

EVERY WAY BUT UP 21

EVERY WAY BUT UP 22

EVERY WAY BUT UP 23

EVERY WAY BUT UP 24

EVERY WAY BUT UP 25

EVERY WAY BUT UP 26

EVERY WAY BUT UP 27

EVERY WAY BUT UP 28

EVERY WAY BUT UP 29

EVERY WAY BUT UP 30

EVERY WAY BUT UP 31

EVERY WAY BUT UP 32

EVERY WAY BUT UP 33