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This article has been tagged since July 2006. Directional drilling (sometimes known as slant drilling outside the oil industry) is the science of drilling non-vertical wells. Directional drilling can be broken down into three main groups; Oilfield Directional Drilling, Utility Installation Directional Drilling (commonly known as H.D.D./Horizontal Directional Drilling) and in-seam directional drilling (Coal-Bed methane). Image File history File links Information_icon. ...
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An oil well is a term for any perforation through the Earths surface designed to find and release both petroleum oil and gas hydrocarbons. ...
Drilling rig in a small oil field Near Sarnia, Ontario, 2001 An oil field is an area with an abundance of oil wells extracting petroleum (oil) from below ground. ...
History
A number of prerequisites were necessary before this suite of technologies could become productive. Probably the first requirement was the realization that oil wells (or water wells, but since their depths are normally trivial, the development was essentially done in the oil industry) are not necessarily vertical. This realization was quite slow, and did not really grasp the attention of the oil industry until the late 1920s when there were several cases of lawsuits alleging that a well drilled from a rig on one person's property had actually crossed the boundary and was penetrating a reservoir on an adjacent property. Initially proxy evidence such as changes in production from pre-existing wells was accepted, but such cases fuelled the development of small diameter tools capable of surveying wells as (or during) their drilling.
Measuring the inclination of a wellbore (its deviation from the vertical) is comparatively simple—one needs a pendulum of some sort. But measuring the azimuth (direction with respect to the geographic grid in which the wellbore is running from the vertical) was much more difficult. In certain circumstances magnetic fields could be used, but were open to the influence of the metalwork used to line wellbores, as well as the metalwork used in drilling equipment itself. The big step forward was in the modification of small gyroscopic compasses by the Sperry company, who were making similar compasses for aeronautical navigation. Sperry did this work under contract to Sun Oil (who were involved in a lawsuit as described above), and a spin-off company was formed under the name "Sperry Sun", which brand continues to this day, absorbed into Halliburton, the second-largest oil services company. The Halliburton subsidiary Sperry Sun had a recent name change to Sperry Drilling Services. ...
Halliburton Energy Services (NYSE: HAL) is a multinational corporation with operations in over 120 countries. ...
Prior experience with rotary drilling had established a number of principles for the configuration of drilling equipment down hole ("Bottom Hole Assembly" or "BHA") that would be prone to "drilling crooked hole" (initial accidential deviations would be increased away from the vertical). Counter-experience had also given these early directional drillers ("DD's", on many whiteboards on many rigs around the world to this day) principles of BHA design and drilling practice which would help bring a crooked hole back towards the vertical.
Combined, these survey tools and BHA designs made directional drilling possible, but it was perceived to be decidedly arcane. Some DDs allegedly took a perverse delight in making it sound more arcane than it actually was - using Ouija boards to perform calculations instead of slide rules for example. Actually the Ouija board performs simple trigonometric functions quickly and in a somewhat graphic format. [citation needed] Ouija (IPA pronunciation: or ) [Or more simply, wee-jee or wee-ja] refers to the belief that one can receive messages during a séance by the use of a Ouija board (also called a talking board or spirit board) and planchette. ...
The slide rule (often nicknamed a slipstick) is a mechanical analog computer, consisting of at least two finely divided scales (rules), most often a fixed outer pair and a movable inner one, with a sliding window called the cursor. ...
The next major advance was in the 1970s, when downhole drilling motors (aka, "mud motors" since they are driven by the hydraulic power of the drilling mud being circulated down through the drill string, out the bit, and back to the surface outside the drill pipe) became commonplace. These allowed the bit to be rotated on the bottom of the hole, while most of the drill pipe was held stationary (power to the motor is supplied by the hydraulic effect of the drilling fluid pumped down the inside of the drill pipe). Including a piece of bent pipe (a "bent sub") between the stationary drill pipe and the top of the motor allowed the direction of the wellbore to be changed without needing to pull all the drill pipe out and place another whipstock. Coupled with the development of MWD (using mud pulse telemetry or EM telemetry, which allows tools down hole to send directional data back to the surface without disturbing routine drilling operations), directional drilling got much easier. Certain profiles could not be drilled without the drill string in rotation at all times. The 1970s decade refers to the years from 1970 to 1979, inclusive. ...
Drilling mud, also called drilling fluid, is a lubricant used while drilling oil and natural gas wells. ...
Mud Pulse Telemetry - The transmition of encoded data through a drilling rigs drilling mud system using rapid fluctuations in the pressure of a closed loop circulating system. ...
Electromagnetism is the force observed as static electricity, and causes the flow of electric charge (electric current) in electrical conductors. ...
The most recent major advance in art of directional drilling has been the development of a range of Rotary Steerable tools from various companies which allow 3 dimensional control of the bit without shutting down the drill string rotation. These tools (PowerDrive from Schlumberger, AutoTrak from Baker Hughes and GeoPilot from Sperry Drilling Services/Halliburton) have almost automated the process of drilling highly deviated holes in the ground. But they are not cheap, so more traditional directional drilling will continue for the foreseeable future. Schlumberger Limited is the worlds largest multinational oilfield services corporation, incorporated in the Netherlands Antilles. ...
Baker Hughes NYSE: BHI is the worlds third-largest oil-services company behind Schlumberger and Halliburton . ...
Sperry Drilling Services is Halliburtons division of MWD (measurement while drilling) and LWD (Logging While Drilling). ...
Halliburton Energy Services (NYSE: HAL) is a multinational corporation with operations in over 120 countries. ...
Until very recently the drive towards lowering the high cost of these devices has been led from outwith the "Big Three" oilfield service companies by individual entrepreneurs and inventors working effectively alone. However, with the advent of a recent acquisition by Halliburton, this is gradually changing and the drive to introduce a viable low-cost Rotary Steerable System is on.
Benefits Directional wells are drilled for a number of purposes: - Increasing the exposed section length through the reservoir by drilling through the reservoir at an angle
- Drilling into the reservoir where vertical access is difficult or not possible. For instance an oilfield under a town, under a lake, or underneath a very difficult to drill formation
- Allowing more wellheads to be grouped together on one surface location can allow fewer rig moves, less surface area disturbance, and make it easier and cheaper to complete and produce the wells. For instance on an oil platform or jacket offshore, where up to about 40 wells can be grouped together. The wells will fan out from the platform into the reservoir deep below. This concept is also being applied to land wells, allowing multiple subsurface locations to be reached using only one leveled-out pad, reducing the environmental impact.
- Drilling "relief wells" to relieve the pressure of a well which is producing without restraint (i.e. a "blow out"). In this scenario, another well could be drilled starting at a safe distance away from the blow out, but intersecting the troubled wellbore beneath the surface. Then, heavy fluid (kill fluid) could be pumped in the new relief wellbore to suppress the high pressures in the original wellbore causing the blowout.
Most directional drillers are given a well path to follow that is predetermined by engineers and geologists before the actual drilling commences. When the directional driller starts the drilling process, he relies on periodic surveys taken with a downhole camera instrument (i.e. "single shot camera") to provide survey data (inclination and azimuth [horizontal direction], aka angle and direction) of the well bore. Drilling The system of spools, valves and assorted adapters that provide pressure control of a production gas or oil well. ...
An oil platform is a large structure used to house workers and machinery needed to drill and then produce oil and natural gas in the ocean. ...
These pictures are typically taken at intervals varying from about 30-500 feet, with 90 feet being common during active changes of angle or direction, and distances of 200-300 feet being typical while "drilling ahead" (i.e. while not making active changes to angle and direction of the well-bore.)
During critical angle and direction changes, especially while using a downhole motor, a MWD (Measurement While Drilling) tool will be added to the drill string so as to provide continuously updated measurements that may be used for (near) real-time adjustments. Misunderstanding While Drilling tools are used by Drilling rigs to transmit information in real time from the tool, located near the drill bit, to the surface. ...
In petroleum drilling technology, a drill string in an oil rig is the column, or string, of drill pipe with attached tool joints that transmits fluid and rotational power from the kelly or top drive to the drill collars and bit. ...
These data indicate to the directional driller whether the well is following the planned well path and possibly the orientation of the drilling assembly when using such methods to cause the well to deviate in a planned manner. Corrections are regularly made by techniques as simple as adjusting rotation speed or the drill string weight (weight on bottom) and stiffness, as well as by more complicated (or time consuming) methods such as introducing a downhole motor.
Such pictures, or surveys, are plotted and maintained as both an engineering and legal record describing the path of the well bore. The survey pictures taken while drilling are typically confirmed by a later survey in full of the borehole, typically using a "multi-shot camera" device.
The multi-shot camera advances the film at time intervals so that by sealing the camera instrument into a tubular housing and dropping the assembly into the drilling string (down to just above the drilling bit), and then withdrawing the drill string at time intervals, the well may be fully surveyed at regular intervals (approximately every 90 feet being common, the typical length of 2 or 3 joints of drill pipe, known as a stand, since most drilling rigs "stand back" the pipe withdrawn from the hole at such increments, known as "stands".)
With modern technology great feats can be achieved. Whereas 20 years ago wells drilled at 60 degrees through the reservoir were achieved with increasing diffulty as deviation angle increased, horizontal drilling is now quite normal.
However, drilling out far from the surface location is still something that requires careful planning and design; the current record holders manage wells of over 10 km (6 miles) away from the surface location at a depth of only 1600–2600 m (5,200–8,500 ft). These are all wells drilled from a land location to underneath the sea (Wytch Farm (BP), south coast of England, ARA (Total), south coast of Argentina (TFE) Dieksand (RWE), north coast of Germany, and most recently Chayvo (ExxonMobil), east coast of Sakhalin Island, Russia. Wytch Farm is an oil field and oil refinery in the Purbeck district of Dorset, England, the largest onshore oil field in Europe. ...
In 1990 Iraq accused Kuwait of stealing Iraq's oil through slant drilling. Such claims are to be seriously doubted to have been serious enough to justify war, or especailly the occupation of Kuwait, since the limits of directional drilling (at the time) made it unlikely that any such well could have been drilled much more than a mile from the surface location. Even doing so would have involved drilling sites in close proximity to the border and the use of sophisticated and easily identifiable equipment and personnel for the most extreme distances.
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