L5-Intro Directional Drilling Coordinate Systems

7/28/2019 L5-Intro Directional Drilling Coordinate Systems

http://slidepdf.com/reader/full/l5-intro-directional-drilling-coordinate-systems 1/32

INTRODUCTION & PETROLEUM REFERENCE SYSTEMS

Arun S Chandel

Assistant [email protected]

09997200339

1



Controlled directional drilling

¾ Directional drilling is the processof directing the wellbore alongsome tra ectory to a

predetermined target.

¾ Controlled directional drillin is atechnique for directing a wellalong a predetermined course to

a bottom hole target located at acertain distance and directionfrom a surface location.

¾ Deviation control is the process

contained within some prescribedlimits relative to inclinationangle, horizontal excursion from

, .





Controlled directional drilling

• As oil companies become more environmentally conscious, itmay be politically advantageous to develop fields fromr ng pa s n sens ve areas.

• In areas of shallow water depth, multiple wells can be drilledrom arti icia is an s.

• Subsea wells are drilled from a template on the ocean floor.In a cases, ocation construction expenses an rig moveexpenses are reduced. Also, due to the close proximity of the wells, production costs are lower.

• However for most land wells, it is usually more economicalto drill vertical wells rather than drill directional wells from a

.



Reasons for directional drilling

¾SURFACE PROBLEMS

¾ SPECIAL NEEDS



Surface Problems

¾ Restricted surface locations

Rig/well positioning problems

1. Unsuitable Terrain (sloped ground, marsh, forest, sand

dunes etc.)

2. Proximity to other wells, pipelines, oilfield facilities

3. Populated area (city or rural area, farmhouse, industrialfacility)

4. Proximity to power lines

5. Airports radar or radio stations

6. Access road and site preparation difficulties

¾ Economics of Rig Positioning

¾ HSE Restrictions



Subsurface Problems

¾ Collision risk with existing wells

u p e arge s o open or pro uc on

¾ Horizontal drain(s) needed

¾ Re-entering producing formations

¾ Drilling extended reach wells (ERD) to remote target(s)

– Faults

– Salt Domes



Subsurface Problems

¾ Fault drilling

¾

Salt dome drilling

¾ Formation Dip

¾ Side-tracking existing wells

¾ To drill relief wells



Special Needs

¾ Controlling vertical wells :Straight hole drilling

¾ Shoreline drilling :to reach offshore reservoirs which areuiet close to the land



Economics- Return on Investment

• Multiple wells from a singlesurface location

• Extended reach - 5-6 miles

•

Extended reach re-entry and-

• More borehole opens the

• More productive intervals in ag ven orma on sequence



Geological Considerations.

Directional drilling is also applicable in fault drilling. It is sometimesdifficult to drill a vertical well in a steeply dipping, inclined fault plane.Often, the bit will deflect when passing through the fault plane, andsometimes the bit will follow the fault plane.

To avoid the problem, the well can be drilled on the upthrown ordownthrown side of the fault and deflected into the producing formation.The bit will cross the fault at enou h of an an le where the direction of the bit cannot change to follow the fault.

2. SALT DOME DRILLING.

drilling has been used to tap some of the oil which has been trapped bythe intrusion of the salt. Instead of drilling through the salt overhangs,the wells can be directionally drilled adjacent to the salt dome and into

e un er y ng raps.However, since the development of salt saturated and oil based muds,the amount of directional drilling has decreased. It is difficult to drill longintervals of salt with fresh water muds. Directionally drilling around thesalt, alleviates a lot of the problems associated with drilling salt.



Geological Considerations.

A highly specialized application for directional drilling is the relief well. If a well blows out and is no longer accessible from the surface, then arelief well is drilled to intersect the uncontrolled well near the bottom.Water or mud are then pumped through the relief well and into the

uncontrolled well. Since it is sometimes required that the relief wellintersect the uncontrolled well, the directional drilling has to beextremel recise and re uires s ecial tools. Surve data is not accurateenough to intersect a wellbore at depth. Proximity logging is requiredwhen drilling relief wells.

.There are special cases when multiple sands are drilled with a singlewellbore. Where steeply dipping sand zones are sealed by anunconformity, fault, or salt dome overhang, a number of vertical wells

wou e requ re o pro uce eac san , w c are separa e y apermeability barrier. However, all the sand zones can be penetrated withone directionally drilled well thereby greatly reducing the cost of production







Geological Considerations: Horizontal Drilling

¾ Horizontal drilling is used to produce thin oil zones with wateror gas coning problems. The horizontal well is optimally placed inthe oil le of the reservoir. The oil can then be roduced at hi hrates with much less pressure drawdown because of the amountof formation exposed to the wellbore.

or zon a we s are use o ncrease pro uc v y rom owpermeability reservoirs by increasing the amount of formation

exposed to the wellbore. Additionally, numerous hydraulic

production and reduce the number of vertical wells required todrain the reservoir.

¾ Horizontal wells can be used to maximize production fromreservoirs which are not being efficiently drained by verticalwells. These wells usually have permeability streaks in

.connect the portions of the reservoir that are productive.



Geological Considerations: Multilateral Wells

Directional drilling can also be used to drill multilateral wells.Multilaterals are additional wells drilled from a parent

Multilaterals can be as simple as an open hole sidetrack or itcan be more complicated with a junction that is cased and haspressure isolation and reentry capabilities.

Multilaterals are used where production can be incrementallyincrease wit ess capita costs. Mu ti atera s can e useoffshore where the number of slots are limited. It is also usedto place additional horizontal wells in a reservoir.



Geological Considerations: ERD¾ Another application of directional drilling is what iscommonly termed extended reach drilling. extended reach

horizontal displacements for the true vertical depth drilled.

¾ Extended reach drilling is used to develop reservoirs withfewer platforms or smaller sections of a reservoir where anadditional platform cannot be economically justified. Extended

reach drilling will become more popular as the cost of p at orms in eeper water an severe environments ecomesmore expensive.



Straight Hole Drilling

Straight hole drilling is a special case of directional drillingwhere an attempt is made to keep the hole vertical. Somereasons for wanting to keep the hole vertical are:1. To keep from crossing lease lines;

2. To stay within the specifications of a drilling contract;3. To stay within the well spacing requirements in a developed field.

¾ In some areas of the world, deviation from vertical is caused bythe natural formation tendencies.

¾ ac e o e assem es are emp oye to eep t e og eg sever tywithin reason.

¾ Pendulum assemblies are used to kee the inclination as low as

possible though with limited success at lower inclinations.

¾ If the inclination is already too great to hit a previously specifiedarge , pen u um assem es, an some mes own o e mo ors are

used to bring the hole back within range of the target.















Major Wellbore Trajectories



Geographical Co-ordinate System

¾ Any position on the earth’s surface can be described in terms of avalue of latitude (degrees north or south of a datum) and a valuefor longitude (degrees east or west of a datum). An imaginaryne wor gra cu e o a u e an ong u e s super mpose on

the globe (earth surface).

¾ The latitude lines or arallels are ima inar circles runnin fromthe equator to both the north and south poles. The equator plane ishalf way between the two poles.The equator is at 0 latitude and the

north pole at 90 N.The south pole is at a latitude of 90 S.

¾ There are ninety latitude lines between the equator and eachpole, each a degree in magnitude. Lines of longitude (or meridianlines) are imaginary lines passing through the north and south

poles and crossing latitude lines at right angles.

¾ Lines of longitude are denoted by a number of degrees from 0-, .

longitude or zero meridian line.In effect the earth has 360 deg of

longitudes.



Geographical Co-ordinate System



Petroleum Industry Co-ordinate Systems

Two of the projection systems most commonly used in the

(UTM), and the Lambert conical orthomorphic.

The Lambert conical projection is used in the USA as it ismost suited to areas where there is a greater extent of east-west and lesser extent of north-south. The Lambert system

produces a projection that has meridians as convergent linesan para e s as arcs o circ es.

The UTM projection is the most commonly used projection

the earth inside the horizontal cylinder and touches thespheroid along a chosen meridian.



Universal Transverse Mercator UTMThe UTM grid is a universal grid which is used to cover the worldexcept for the polar regions. The UTM is based on 60 zones, each is 6degrees of longitude wide and extends from 80 deg S to 84 deg N

latitude, with the International metre being used as the unit of measurement (not foot). Greenwich in England is chosen as the

.

Each of the 60 zones is defined by meridians; for example, zone 31

has the zero meridian on the left (Greenwich) and the 6 deg Eastmeridian on the right.

For the polar regions North of 84 deg N and South of 80 deg S, a, ,

used.



UTM Coordinates

coor na es are g ven as or ngs an as ngs an are a wayspositive numbers and measured in meters.The Northing coordinate is the distance from the equator and theeastin coordinate is the distance from a line 500 000 m west of thecentral meridian for that sector.

Northingse equa or s c osen as e a u e o or g n n a zones. or e

northern hemisphere, false northing numbers are given to latitudesbeginning with 0 metres at the equator and increasing towards the

north. For the southern hemisphere, the equator is given arbitrary of northing value of 10,000,000 metres to avoid negative numbers.Northings in the southern hemisphere decrease towards the south thepole.

EastingsThe central meridian of each zone is given an arbitrary eastingcoordinate of 500,000 metres East to avoid negative numbers. Falseeasting numbers are then given to each vertical grid line, decreasingwestwards and increasing eastwards in each zone.





Date post:	03-Apr-2018
Category:	Documents
Upload:	kexadex2
View:	219 times
Download:	1 times

L5-Intro Directional Drilling Coordinate Systems

Documents