Diamond drilling handbook pdf

Sapiens: A Brief History of Humankind. A drilling machine comes in Download as PDF. Accessories for diamond drilling Page Diamond coring consumables. Previous Previous post: Crane fluid flow handbook edition pdf. Next Next post: Dnd dungeon master handbook. For more info, please view; the table of contents, and the book's forward. If you like what you see, go directly to the Order Page to obtain your copy.

Diamond drill handbook. James Deans Cumming 0 Reviews. From inside the book. What people are saying - Write a catcher Core Drill core recovery coring bit cost deflecting wedge degrees depth diabase diameter diamond bit Diamond Core Drill diamond drill holes diamond drilling dimensions Double Tube Core drill bit drill hole drill pipe.

The emphasis is on the theory behind these drilling elements in order to develop a greater understanding of the principles involved in drilling a.

A reference for all those involved in the diamond drilling industry - from the field geologists to the driller on the rig and the chargehand in the workshop. It covers basic geology, wireline drilling, drilling fluids, fishing operations, hydraulics, pumps, derricks, and more.

Free shipping for many products. Condition: New. A Defence of Moderate Non-Conformity. Diamond Drilling Handbook history This three part series takes a look back through more than years to explore what it is that has made the Diamond Drilling Handbook such an enduring publication.

It includes references to how the Handbook was written, the industry activity at the time it was conceived and a brief look at the history of.

Open Library is an open, editable library catalog, building towards a web page for every book ever published. Diamond drilling handbook by W. Heinz,Heinz edition, in English - 2d ed. Licensed experts in well drilling. Pumps and water treatment. Call Drilling Books.

Diamond drilling definition: drilling using a drill with a diamond-impregnated bit Meaning, pronunciation, translations and examples. Drill holes begin with installing a pipe called casing from the surface through soils and sealed into bedrock. Diamond core drilling uses a diamond bit, which rotates at the end of drill rod or pipe inside the casing.

The opening at the end of the diamond bit allows a solid column of File Size: 4MB. The first edition of the "Drilling Data Handbook" was printed in In more than six decades, the book has been improved, adding lots of new technologies and equipment in its eight additional editions.

But its principle is to remain familiar and friendly to : Handbook of Best Practices for Geothermal Drilling. This is referred to as "sapropelic" matter and is a good source for oil. Marine equivalents are also known. Such sediments may form in lagoons behind a reef. The rocks are bent and fractured. The study of the structures that result and the processes that form them is called Structural Geology. If the rock layers on one side of a fracture have moved in relation to the other side, the fracture is called a fault Figure Displacement - or how far apart the sides of the fault have moved - may range from only a few inches to many miles, as along the San Andreas fault in California.

Figure Normal Fault 2. The names are derived from the movement of adjacent blocks. Movement is up or down in normal and reverse faults but is mainly horizontal in thrust and lateral faults.

A combination of vertical and horizontal movements is also possible in all faults. Rotational faults and upthrusts Figure are variations of normal and reverse faulting. They are most important to the petroleum geologist because they affect the location of oil and gas accumulations. Figure Reverse fault. Earth movements often bury or prevent the depositing of part of a sediment series that is present elsewhere.

Such buried erosion surfaces are called unconformities. Two general kinds of unconformities are the disconformity and the angular Figure Earth movements are most important to petroleum geology because they produce barriers that cause a large proportion of petroleum accumulations. As compressional forces increase, the folds become tighter and the limbs drop more steeply. Assymetric folds are ones in which one limb dips more steeply than the other.

These dips can eventually become greater than vertical and folds become overturned. Axial plane cleavage can develop which is caused by alignment of platey minerals parallel to the fold axis. With increasing deformation this cleavage can dominate the structure of the rock, obliterating the original bedding. Fold axes need not be horizontal, in which case they are said to plunge.

If more than one episode of the folding takes place, then the axial planes cleavage developed by the first phase may itself be folded. This is then known as superimposed folding and can often be recognized by statistical analysis of several fold axes in one area. Figure Folding and cleavage Folding in sedimentary rocks is important as it creates the potential for oil traps on the Crest of folds, and these are a major cause of hydrocarbon accumulations. They typically occur in Limestones and Dolomites due to solution along natural planes of weakness by percolating underground waters, or by removal of overlying weight of rock by erosion which allows the rock to expand slightly from stress release, and fracture.

They normally develop in three planes, all at right angles, and often have a strong control on the geomorphology of the area. Jointing in the rocks can lead to large volumes of porosity and is an important reservoir type, particularly in carbonate rocks. It can also give lost circulation problems when drilling a highly jointed or cavernous area. An unconformity is any break in the geological sequence. The origin of coal on land is a process similar to the origin of petroleum in the sea.

In the formation of coal, dead vegetation in the absence of oxygen ceases to decompose and accumulates as humus in the soil and as deposits of peat in bogs and swamps. Peat buried beneath a cover of clays and sands becomes compacted. As the weight and pressure of the cover increase, water and gases are driven off. The residue, very rich in carbon, becomes coal. In the sea a similar process takes place. An abundance of marine life is eternally falling in a slow, steady rain to the bottom of the sea.

Vast quantities of matter are eaten or oxidized before they reach the bottom but a portion of this microscopic animal and plant residue escapes destruction and is entombed in the ooze and mud on the sea floor. The organic debris collects in sunken areas at the bottom and is buried within an ever-increasing accumulation of sands, clays and more debris until the sediment is thousands of feet thick.

As the sediment builds, the pressure of deep burial begins to work. Bacteria take oxygen from the trapped organic residues and gradually break down the matter, molecule by molecule, into substances rich in carbon and hydrogen. The extreme weight and pressure of the mass compacts and squeezes the clays into hard shales. Within this deep. To be commercially productive, it must be big enough, be thick enough, and have enough pore space to contain an appreciable volume of hydrocarbons. Also, it must give up the contained fluids at a satisfactory rate when the reservoir is penetrated by a well.

Sandstones and carbonates such as limestone and dolomite are the most common reservoir rocks. Connected pores allow petroleum to move from one pore to another. Hydrocarbons will move ever upward until they escape at the surface unless something stops the movement.

Therefore, a barrier, or trap, is needed to impede this migration in order to get subsurface accumulation of petroleum. A trap is produced by geological conditions that cause oil and gas to be retained in a porous reservoir. Reservoir traps for hydrocarbons have two general forms: 1 an arched upper surface, commonly called structural and 2 an up-dip termination of porosity, called stratigraphic Figure Figure Simplified diagram of the Milano, Texas fault.

Structural traps vary widely in size and shape. Some of the more common structural traps are anticlinal traps, fault traps and dome and plug traps. Figure Simple faults - normal a , reverse b , thrust c and lateral d 2. Two general kinds of stratigraphic traps are the disconformity and the angular unconformity, both resulting from unconformities.

Examples of reservoirs of this nature are the many reservoirs found in the Seeligson field in Southwest Texas or parts of the East Texas field. Figure In map view, fault traps may be simple a or compound b Figure Discontinuous peripheral traps around piercement salt dome 2. Oil, water, and gas are all fluids; oil and water are liquids as well as fluids; gas is a fluid but not a liquid.

Consequently, these sedimentary beds were originally saturated with salt water. However, part of this water was displaced by petroleum when it was formed. Salt water that remains in the formation is called formation water. However, oil will not displace all the original water. A film of water sticks to, or is absorbed by, the solid rock material surrounding the pore spaces.

The film of water lining the pores is called wetting water. In other words, water is not only in the reservoir below the oil accumulation, but also within the pores along with the oil.

The energy supplied by gas under pressure is probably the most valuable drive in the withdrawal of oil from reservoirs. The industry has come a long way since the day it was general practice to "blow" gas caps into the atmosphere, so that a well in the gas zone of a reservoir could finally be induced to produce a little crude oil. Gas is associated with oil and water in reservoirs in two principal ways as solution gas and as free gas in gas caps. Practically all reservoirs have water in the lowest portions of the formation, and the oil lies just above it.

However, no sharp line divides the oil and water, nor is the contact line horizontal throughout a reservoir. Actually, the oil-water contact is a zone of part water and part oil, and this zone may be from 10 to 15 feet thick. The gas-oil contact has somewhat the same properties. However, because oil is much heavier than gas, oil does not tend to rise as high into the gas zone as water does into the oil zone. Contrary to what might seem logical, all the rocks that overlie a buried reservoir do not create pressure in the reservoir under normal circumstances.

In any case, as long as the reservoir has some ultimate outlet to the surface, the pressure in it is caused only by the water and is considered to be normal pressure. In such cases, the overlying rock formations do have a bearing on reservoir pressure.

What happens in this case is that the heavy weight of the overlying beds presses down and squeezes the reservoir. Since the water in the reservoir cannot escape to the surface, the reservoir pressure builds up to abnormally high amounts. In this case, the reservoir does connect with the surface. However, the outcrop to the surface is on the side of a hill or mountain, at an elevation much higher than the part of the reservoir buried below the level plain.

A well drilled at this point spouts water like a fountain. The water tries to seek its own level. Such wells are called artesian wells. However, a minimum competence in algebra and trigonometry is required. In order to understand how wells are planned, trigonometry is necessary. When doing projections, planning, etc. If plotted in rectangular X-Y coordinates, it gives a straight line. The slope of the line is 2. The intercept is These are called supplementary angles.

Parallel lines meet at infinity. Find the other angles. Therefore, if we know any two angles in a triangle, we can calculate the third one. The ratio of the sides of similar triangles is constant.

The cosine of one complementary angle is the same as the sine of its complement, e. Knowing the values of two components, we can solve for the other components. Note This is how we calculate Horizontal Displacement or Closure from the rectangular coordinates. Otherwise, there will be no triangle. In Figure , parallel lines 1 and 2 are cut by two other parallel lines 3 and 4.

CD is the perpendicular bisector of the chord. It goes from the centre of the chord to the circumference of the circle, following the direction of the radius at that point. It touches the circle at only one point E , the point of tangency. A radian is defined as the angle at the centre of the circle when the length of the arc is 1. Consider Figure We can see why in Figure Figure Projections of lines The projection of one line onto any other line is equal to the length of the line times the cosine of the angle formed between the two lines.

If the lines don't meet, simply draw a line parallel to the other line. The angle a is formed between them. The projection of AB is AB'. Knowing the buildup rate BUR , we can calculate the value of Rc. Figure Radius of curvature definitions 2. The various systems of coordinates used in the oilfield are discussed and compared. The different survey calculation methods are described.

Understanding how a well plan proposal for a directional well is calculated is one of the most important duties of the DD, particularly if he is working as an FSM or manager. The basics of well planning are covered in this chapter. One of the biggest mistakes a DD can make is to collide with another well. This chapter describes the implications and dangers of kicking off close to other wells. The uses of volume of uncertainty and traveling cylinder in anti-collision analysis are explained.

Although computer-based DD software is used to do multiwell anti-collision calculations, the DD must understand what is actually being calculated. It is dangerous to blindly accept the outputs from any computer program. It is advisable that the trainee DD plot surveys by hand on the "Spider" plot in order to get familiar with anti-collision techniques. Objectives of this Chapter On completing this chapter the directional driller should be able to do the following exercise: 1.

Describe the various systems of coordinates used in the oilfield. List the various methods of calculating a directional survey.

Calculate a few surveys by hand with a scientific calculator using the Average Angle method. Explain what preliminary information for the directional well is needed from the client.

Describe the effect on maximum angle of changing the kickoff point. Explain the implications of high buildup and dropoff rates from a drilling standpoint. Describe the four most common types of directional well profile. Explain the principle behind the traveling cylinder method of anti-collision analysis. Explain what is meant by Ellipse of Uncertainty.

Just as man evolved from relative to absolute positioning, the oil industry has evolved from relative i. The need to interchange meaningful data with others, government regulations, the requirement to locate the blow out wellbore when the surface rig has cratered, and many other equally important reasons require that the DD of today understand far more about positioning and coordinate systems.

Well, really it is an oblate spheroid a squashed sphere. The radius of the earth at the North pole is about 13 miles shorter than the radius at the Equator. If the earth was the size of a billiard ball, the human eye could not tell the difference; but, when it comes to modeling the size and shape of the border of a country or an oilfield lease this 13 miles causes many problems for the geodesist a scientist who studies the shape of the earth.

The maps and drawings used in directional drilling are flat. Plotting data which lies on the surface or subsurface of a sphere onto a flat map is impossible without compromises and the introduction of controlled error. The science of geodesy and cartography map making are drawn upon heavily to provide a complex, yet straight forward method for the DD to represent and plot his surveys and wellplans.

They are commonly referred to as meridians and parallels, respectively. Given the North and South Poles, which are approximately the ends of the axis about which the Earth rotates, and the Equator, an imaginary line halfway between the two poles, the parallels of latitude are formed by circles surrounding the Earth and in planes parallel with that of the Equator.

If circles are drawn equally spaced along the surface of the sphere, with 90 spaces from the Equator to each pole, each space is called a degree of latitude. The circles are numbered from 0 at the Equator to 90 North and South at the respective poles. Each degree is subdivided into 60 minutes and each minute into 60 seconds of arc.

Meridians of longitude are formed with a series of imaginary lines, all intersecting at both the North and South Poles, and crossing each parallel of latitude at right angles, but striking the Equator at various points. If the Equator is equally divided into parts, and a meridian passes through each mark, degrees of longitude result.

These degrees are also divided into minutes and seconds. While the length of a degree of latitude is always the same on a sphere, the lengths of degrees of longitude vary with the latitude see Figure At the Equator on the sphere, they are the same length as the degree of latitude, but elsewhere they are shorter.

It, thus, becomes necessary to choose arbitrarily one meridian as the starting point, or prime meridian. There have been many prime meridians in the course of history, swayed by national pride and international influence. Eighteenth-century maps of the American colonies often show longitude from London or Philadelphia. During the 19th century, boundaries of new States were described with longitudes west of a meridian through Washington, D.

In , the International Meridian Conference, meeting in Washington, agreed to adopt the "meridian passing through the center of the transit instrument at the Observatory of Greenwich as the initial meridian for longitude," resolving that "from this meridian longitude shall be counted in two directions up to degrees, east longitude being plus and west longitude minus" Brown, , p.

When the map is completed with labels, the meridians are marked with respect to the Greenwich Prime Meridian. The formulas in this bulletin are arranged so that Greenwich longitude may be used directly.

The concept of latitudes and longitudes was originated early in recorded history by Greek and Egyptian scientists, especially the Greek astronomer Hipparchus 2nd century, B. Claudius Ptolemy further formalized the concept Brown, , p. Because calculations relating latitude and longitude to positions of points on a given map can become quite involved, rectangular grids have been developed for the use of surveyors.

In this way, each point may be designated merely by its distance from two perpendicular axes on the flat map. Specifically, an oblate spheroid is an ellipse rotated about the shorter semi-minor axis. The oblate spheroid is the principal shape used in modeling the surface of the earth. The Earth is not an exact ellipsoid, and deviations from this shape are continually evaluated.

For map projections, however, the problem has been confined to selecting constants for the ellipsoidal shape and size and has not generally been extended to incorporating the much smaller deviations from this shape, except that different reference ellipsoids are used for the mapping of different regions of the Earth. There are over a dozen principal ellipsoids which are used by one or more countries. The different dimensions do not only result from varying accuracy in the geodetic measurements the measurements of locations on the Earth , but the curvature of the Earth's surface is not uniform due to irregularities in the gravity field.

Until recently, ellipsoids were only fitted to the Earth's shape over a particular country or continent. The polar axis of the reference ellipsoid for such a region, therefore, normally does not coincide with the axis of the actual Earth, although it is made parallel. The discrepancy between centers is usually a few hundred meters at most.

Only satellite-determined coordinate systems, such as the WGS 72, are considered geocentric. They usually consist of the definition of an ellipsoid, a definition of how the ellipsoid is oriented to the earth's surface, a definition for the unit of length, an official name, and region s of the earth's surface for which the datum is intended to be used. The reference ellipsoid is used with an "initial point" of reference on the surface to produce a datum, the name given to a smooth mathematical surface that closely fits the mean sea-level surface throughout the area of interest.

Once a datum is adopted, it provides the surface to which ground control measurements are referred. The projection equations of large-scale maps must use the same ellipsoid parameters as those used to define the local datum; otherwise, the projections will be inconsistent with the ground control.

Geodetic datums are part scientific and part political. The most common family of positioning methods is X Y Cartesian coordinates.

Ninety nine percent of the earth's wellbores are located by some form of X Y coordinate system. Map projections are defined in a specific unit of length. They usually have defined coefficients which vary with the location on the surface of the earth. A worldwide specification of the variable coefficients, called the Universal Transverse Mercator UTM is the most commonly used member of the TM family. The Lambert map projection is also common throughout the world and is currently the most used projection in the U.

The quadrangles formed by the intersection of these lines normally referred to as parallels and meridians, respectively are of different shapes and sizes, which severely complicates the locations of points and the measurement of directions. Polar regions are covered by other, special projections. See Figure Each zone is flattened and a square imposed on it.

Thus, its outer edges are curved when drawn on a flat map since they follow the meridian lines on the globe. Each of the 60 zones is numbered, starting with zone 1 at the th meridian.

The areas East and West of the Greenwich Meridian are covered by zones 30 and It is not essential to use the grid sector letter to identify the position of a point on the globe. To avoid negative values for eastings, the central meridian in any zone is assigned the arbitrary eastings value of ,m.

Along the equator a zone is about , meters wide, tapering towards the polar region. Eastings range in value from approximately , to , For points north of the equator, northings are measured directly in meters, with a value of zero at the equator and increasing toward the north.

To avoid negative northing values in the S. Hemisphere, the equator is arbitrarily assigned a value of 10,, meters and displacements in the southern hemisphere are measured with decreasing, but positive, values as one heads south.

Clearly, at the central meridian, Grid North equals True North. Convergence will vary with distance away from the central meridian and with distance away from the equator. Convergence is negative to the East and positive to the West. However, the well surveys will use sensors that reference either Magnetic or True North, and the user must therefor be able to convert from one reference to the other. Lambert yields the greatest similarity that any plane figure can have with one drawn on the surface of a sphere.

Meridiens are equally-spaced radii of the concentric circular arcs representing parallels of latitude; the parallels become further apart as the distance from the central parallels increases. Straight lines between points approximate great circle arcs for maps of moderate coverage.

Two parallels may be made standard or true to scale. In the State Plane Coordinate System SPCS for States using the Lambert projection, the choice of standard parallels has the effect of reducing the scale of the central parallel by an amount which cannot be expressed simply in exact form, while the scale for the central meridien of a map using the Transverse Mercator projection is normally reduced by a simple fraction. North America is illustrated here to show the change in spacing of the parallels.

When used for maps of the conterminous United States or individual States, standard parallels In the U. A Transverse Mercator system was prepared for the remaining States. One or more zones is involved in the system for each State. The U. K National Grid are two common examples. In the State Plane Coordinate System of , NAD27 is the geodetic datum, a foot is the unit of length, three different map projections are used depending upon where in the U.

Coast and Geodetic Survey predecessor at the National Ocean Service to enable surveyors, mappers, and engineers to connect their land or engineering surveys to a common reference system, the North American Datum of It is impossible to map a curved Earth an a flat map using plane-coordinates without distorting angles, azimuths, distances, or area.

Three conformal map projections were used in designing the original State plane coordinate systems, the Lambert conformal conic projection, the transverse Mercator projection, and the oblique Mercator projection.

The Lambert projection was used for States that are long in the east-west direction e. The transverse Mercator projection was used for States or zones within States that are long in the north-south direction e. These same map projections are also often custom designed to provide a coordinate system for a local or regional project. For example, the equations of the oblique Mercator projection produced project coordinates for the Northeast Corridor Rail Improvement project when a narrow coordinate system from Washington, DC, to Boston, MA, was required.

Land survey distance measurements in the s were typically made with a steel tape, or something less precise. Accuracy rarely exceeded one part in 10, Therefore, the designers of the SPCS 27 concluded that a maximum systematic distance scale distortion attributed to the projection of , could be absorbed in the computations without adverse impact on the survey.

If distances were more accurate than ,, or if the systematic scale distortion could not be tolerated, the effect of scale distortion could be eliminated by computing and applying an appropriate grid scale factor correction. Admittedly, the one in 10, limit was set at an arbitrary level, but it worked well for its intended purpose and was not restrictive on the quality of the survey when grid scale factor was computed and applied. There was usually sufficient overlap from one zone to another to accommodate projects or surveys that crossed zone boundaries and still limit the scale distortion to , In more recent years, survey accuracy usually exceeded , More surveyors became accustomed to correcting distance observations for projection scale distortion by applying the grid scale factor correction.

When the correction is used, zone boundaries become less important, as projects may extend farther into adjacent zones. Some geodesists advocated retaining the design of the existing State plane coordinate system projection type, boundaries, and defining constants and others believed that a system based on a single projection type should be adopted. The single projection proponents contended that the present SPCS was cumbersome, since three projections involving zones were employed.

A study was instituted to decide whether a single system would meet the principal requirements better than SPCS These requirements included ease of understanding, computation, and implementation. Initially, it appeared that adoption of the Universal Transverse Mercator UTM system would be the best solution because the grid had long been established, to some extent was being used, and the basic formulas were identical in all situations. However, on further examination, it was found that the UTM 6 degree zone widths presented several problems that might impede its overall acceptance by the surveying profession.

For example, to accommodate the wider zone width, a grid scale factor of , exists on the central meridian while a grid scale factor of , exists at zone boundaries. As already discussed, similar grid scale factors on the SPCS rarely exceeded , In addition, the "arc-to-chord" correction term that converts observed geodetic angles to grid angles is larger, requiring application more frequently.

And finally, the UTM zone definitions did not coincide with State or county boundaries. These problems were not viewed as critical, but most surveyors and engineers considered the existing SPCS 27 the simpler system and the UTM as unacceptable because of rapidly changing grid scale factors. This grid met the primary conditions of a single national system.

By reducing zone width, the scale factor and the arc-to-chord correction would be no worse than in the SPCS Furthermore, seldom did this cause larger scale factor or arc-to-chord corrections than in the existing SPCS 27, although several of the larger counties would require two zones.

However, the average number of zones per State was increased by this approach. The grids had been in use for more than 40 years and most surveyors and engineers were familiar with the definition and procedures involved in using them. With availability of electronic calculators and computers, little merit was found in reducing the number of zones or projection types.

There was merit in minimizing the number of changes to SPCS legislation. The project was undertaken because NAD 27 values could no longer provide the quality of horizontal control required by surveyors and engineers without regional recomputations least squares adjustments to repair the existing network.

NAD 83 supplied the following improvements: One hundred and fifty years of geodetic observations approximately 1. These ellipsoidal parameters are often embedded in the mapping equations and their change produces different plane coordinates.

This local system depends upon and has a direct relationship to all the concepts presented thus far in this chapter. Many assumptions are often made in defining local coordinate systems which are not obvious, but very important. The term Reference Point will be used in this chapter to mean either or both. This reference point has only North and East coordinates defined. Unless specifically defined otherwise, a Local Coordinate System has each of its axis oriented parallel to the corresponding axis of the "legal" coordinate system in which its Reference Point is defined.

Obviously, there must be a defined unit of length, however, this is normally dictated by the customer's preference or governmental regulation. By definition, a Local Coordinate System is a grid system and has to use a Grid North in order to be plotted correctly.

Only on a plot drawn using Grid North, can distances and angles be measured directly. If True North or Magnetic North is used to plot directional survey data, the relationships between lines and points on the plot are not linear and therefore can not be measured directly with a compass or ruler.

Quite often, the error distortion is small, but this is not something that is readily apparent and can not be left to individual judgment. In many cases, governmental reporting requirements are dictating the use of Grid North.

Under no circumstances should Anadrill employees prepare or use a well plan based upon a Local Coordinate System which uses anything but Grid North. Requests from a customer to do this should be directed to Senior management and technique and will be evaluated on a case by case basis. Often, it is necessary to convert location data from one local" coordinate system to another. The slot locations on this drawing are usually defined relative to a drawing local reference system which has its own origin and reference North.

It is up to the planner to determine the amount of translation moving the pattern in N, E and rotation moving the pattern around a point required to allow the slots to be located in the DD's local coordinate system. These reference lines should be referred to as Structure Reference Lines.

An analogous discussion can be made for relocating Targets from a geophysical or reservoir based reference system to the Local Coordinate System. Values of magnetic declination change with time and location. As the movement of Magnetic North is constant and predictable, Magnetic declination can be calculated for any given point on the earth at any given time.

Charts depicting the various declinations and rate of change usually expressed as an annual change are widely used. An Easterly declination is expressed as a Positive value and a Westerly declination is expressed as a Negative value.

Although converting from one reference to another appears a simple task, considerable care is needed, depending on the relative directions of convergence and magnetic declination.

For example, see Figure Figure Corrections to survey azimuth 3. Any point within a lease can usually be defined in terms of distance from any two adjoining boundaries Figure In this method, lines are surveyed along the irregular edges of the property and the azimuth and length of the lines recorded. When a well is placed in this type of property, the well location is often described as in the following example See Figure In this case, there are no references defined to a national or international measurement system.

This method has been used for the majority of the wells drilled in Texas. With land wells, the surface location of the well will usually be determined by the factors originally prompting the decision to drill a deviated as opposed to a vertical well. Offshore platforms tend to have between 6 and 60 wells. Adjacent wells may have only 6' feet between centers. Many factors which directly affect installations including water depth, bottom slope, sandy bottom versus coral reef, local currents, etc.

A directional well can have one or more objectives. The most obvious of the objectives is the target. These can be geological structures, geological features such as faults or pinch-outs, other wellbores as in relief well drilling or a combination of these. In this section, we look at the way in which targets are defined. As we have seen, there are various ways of referring to a surface location UTM, Lambert, Geographic, etc. The same is true for the target location, with the addition of the vertical depth of the target.

When planning and drilling a well, it is simpler to use local coordinates when referring to the target. Once the exact location of the local reference point and the target are known, the local coordinates can easily be determined. They can easily be derived by subtracting the grid coordinates of the surface location from those of the target.

For example: Table Rectangular coordinates of a target position. A negative value denotes South or West. Polar coordinates can be derived from the rectangular coordinates. They are expressed as a Distance Departure and a Direction either Quadrant or azimuth. The tan function on most calculations normalizes the answer to a value between 0 and 90 degrees. Always restore your azimuth to the correct quadrant. From O, there are three axes; to North, to East and "z" vertical down. The distance is SB 3.

The distance is B3B2. Usually, the Vertical Section passing through the center of the Target is used for plotting the well profile. In order to ascertain the latest bottom-hole position, it is necessary to perform a survey calculation which includes the three inputs listed above.

Projections to the target, etc. A number of survey calculation methods have been used in directional drilling. The Tangential Method is the oldest, least sophisticated and most inaccurate method. This method should never be used. Average Angle and Radius of Curvature methods are in common field use.

Average Angle method in particular lends itself easily to a hand-held calculator. Radius of Curvature method is more widely used. However, official survey reports should not use either if the above methods except when demanded by the customer. Minimum Curvature method should be used for all office calculations and official survey reports. Where possible, it should also be the field calculation method chosen.

The DD is advised to have at the well-site a hand-held calculator which is programmed for both Radius of Curvature and Minimum Curvature methods of survey calculation. The well bore is then assumed to be tangential to these angles. On any curved section of the hole there are flaws in this assumption and this method of survey calculation cannot provide realistic results for anything but a hold section of the well.

In a build and hold well, the TVD would be less i. With the well turning to the right in the North East quadrant, one would introduce errors that would result in a position too far to the East, and not far enough to the North. Effectively, the course length between the two survey points is divided into two, equal length, straight line segments. The errors that remain tend to show too great a TVD, and too little displacement during the build section. Although its accuracy is comparable to the average angle method, this method is not commonly used since the formulae are more complicated.

Figure This is then the assumed well path, with a length equal to the actual course length between the two stations. As such the well bore can be curved in both the vertical and horizontal planes Figure To be more specific, it takes the space vectors defined by the inclination and azimuth at each of the survey points and smooths these onto the well bore by use of a ratio factor which is defined by the curvature of the well bore section.

This curvature is the Dog-leg Figure Figure Minimum curvature - dog leg This method provides one of the more accurate methods for determining the position of the well bore. We can then determine the increments along the three axes, to define the position of the second survey point. It is the Anadrill method of choice. It combines the tangential and balanced tangential calculation methods, and takes into account the length of the survey tool STL.

It treats the portion of the course over the length of the survey tool as a straight line i. Compared to the "actual" TVD of