Introduction to Directional Drilling

Introduction to Directional DrillingControlled directional drilling is the science and art of deviating a wellbore along a planned course from a starting location to a target location, both defined with a given coordinate systemHistorical Development of Directional Drilling

Directional drilling was initially used as a remedial operation.

Interest in controlled directional drilling began about 1929 after new and rather accurate means of measuring the hole angle were introduced during the development of the Seminole field, Oklahoma, USA.The acid bottle inclinometer & Inclinometer with a magnetic needle, 1920sIntroduction to Directional DrillingBoth systems were used on Seminole Field, Oklahoma. A glass cylinder filled with hydrofluoric acid was lowered into the well, the acid etches the level surface of the acid on the glass giving a reading for well inclination. Magnetic needle used earth gravitational field to calculate well inclination giving better results than the acid bottle.

Introduction to Directional DrillingEarly version of the single shotSignal Hill field in Long BeachWild well killed near Conroe, Texas1934sIn the early 1930s the first controlled directional well was drilled in Huntington Beach, California. The well was drilled from an onshore location into offshore oil sands. An early version of the single shot instrument was used to orient the whipstock.In 1933, during the development of the Signal Hill field in Long Beach, California, several wells were drilled under the Sunnyside Cemetery from locations across the streets surrounding the cemetery and even from more distant points to tap a productive zone underlying the cemetery.An offset well drilled and deviated so that it would bottom out near the borehole of the cratered well. Then mud under high pressure could be pumped down this offset well so that it would channel through the formation to the cratered well and thus control the blow out.Introduction to Directional Drilling2.Types of WellsExploration Sometimes called wildcat wells, probe the earth where no known hydrocarbons exist to determine whether oil or gas are present in a subsurface rock formation

AppraisalAre drilled to determine the extent of a field or the amount of area it covers

Development or ProductionAre drilled in an existing field to remove the obtainable hydrocarbons

Introduction to Directional Drilling3. Directional Well Profiles

J Type WellIntroduction to Directional Drilling3. Directional Well Profiles

S Type WellIntroduction to Directional Drilling3. Directional Well Profiles

Horizontal Well7Introduction to Directional Drilling3. Directional Well Profiles

Negative Section Well8Introduction to Directional Drilling3. Directional Well ProfilesA directional well profile is the planned well trajectory from the surface to the final drilling depth by projecting the wellbore onto two plotted planes. In order to determine the best geometric well profile from the surface to the bottomhole target, the following information must be known

Position of the surface location, Position of the target location, and True vertical depth (TVD).Features of A Directional Well Profile9Introduction to Directional Drilling3. Directional Well Profiles

Kickoff Point (KOP)The kickoff point is the location at a given depth below the surface where the wellbore is deviated in a given direction.Surface LocationThe surface location is any designated point at surface where the well will start to be drilled.Features of a Directional Well Profile10Introduction to Directional Drilling3. Directional Well ProfilesEnd of Buildup (EOB)The end of buildup is the location where the wellbore has finished increasing.Well InclinationThe well inclination is the angle by which the wellbore deviates from the vertical.Features of a Directional Well Profile

11Introduction to Directional Drilling3. Directional Well ProfilesTangent SectionOccurs where the inclination is held constant for a certain distance. There could be an additional build or drop before reaching the target.Hold AngleThe hold angle occurs where the inclination of the borehole is held constant.Features of a Directional Well Profile

12Introduction to Directional Drilling3. Directional Well ProfilesEnd of Drop (EOD)The end of drop is the location where the wellbore finishes dropping inclination.Start of Drop (SOD)The start of drop is the location where the wellbore starts dropping inclination.Features of a Directional Well Profile

13Introduction to Directional Drilling3. Directional Well ProfilesTarget DisplacementThe target displacement is the lateral distance from the surface location to the target.Features of a Directional Well Profile

Target LocationThe target location is a point defined in space by geographical coordinates at a given true vertical depth. A well profile could have multiple targets.14Introduction to Directional Drilling3. Directional Well ProfilesTurn RateThe turn rate determines the rate a well profile turns in azimuth direction. Usually expressed in degrees per 100 ft or degrees per 30 m.Features of a Directional Well ProfileDrop off RateThe drop off rate is the rate at which the inclination decreases. The rate is usually expressed in degrees per 100 ft or degrees per 30 m of the course length.Build up RateThe buildup rate is the change of inclination of a wellbore where the angle is increased. The rateis usually expressed in degrees per 100 ft or angular increase per 30 m of the measured depth.Dog Leg Severity (DLS)A normalized estimate (e.g., degrees/ 100 feet) of the overall curvature of an actual well path between two consecutive survey stations.15Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well Profile

True Vertical DepthThe true vertical depth of any point or station along a wellbore is the vertical distance from the well surface reference point to the station of interest.16Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well Profile

Measure Depth (MD)The measured depth of any point or station along a wellbore is the distance from the well surface reference point to the station of interest along the actual well path.17Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well ProfileVertical Section (VS)The vertical section is the distance between any two points along a wellbore projection onto a vertical section plane.

18Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well Profile

Horizontal Displacement (HD)The horizontal displacement is the distance between any two points along a wellbore projected onto a horizontal plane or plan view.AzimuthThe azimuth is the angle in the horizontal plane measured from a fixed reference direction (such as True North), usually measured clockwise19Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well ProfileQuadrantThe quadrant bearing of a well is the angle in the horizontal plane measured from either a North or South reference direction towards the East or West, defining the direction of the wellbore.

20Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well ProfilePolar CoordinateThe polar coordinate of a point is the distance projected in a horizontal plane from a fixed reference point and the angle of this line from a reference direction (usually True North).

21Introduction to Directional Drilling3. Directional Well ProfilesFeatures of a Directional Well ProfilePolar CoordinateThe rectangular coordinates of a point are defined as the projected distance along two reference axes which are at right angles, the distance being measured from the intersection of the axes along the axes. These axes reside in the horizontal plane and typically are north/south and east/west directions.

22SUMMARYWhat is a Survey ? A survey, or more appropriately a survey station, consists of the following components:

Inclination Hole Direction (Azimuth) Measured Depth

Survey data tells the directional driller where the hole has been.Introduction to Directional DrillingIntroduction to Directional Drilling3. Directional Well Profiles

24Introduction to Directional Drilling4. Directional Drilling Aplications

SidetrackingIntroduction to Directional Drilling3. Directional Drilling Aplications

Inaccessible LocationsIntroduction to Directional Drilling3. Directional Drilling Aplications

Salt Dome DrillingIntroduction to Directional Drilling3. Directional Drilling Aplications

Fault ControllingIntroduction to Directional Drilling3. Directional Drilling Aplications

Multiple Exploration Wells from a Single WellboreIntroduction to Directional Drilling3. Directional Drilling Aplications

Onshore Drilling to Offshore LocationsIntroduction to Directional Drilling3. Directional Drilling Aplications

Offshore Multiwell DrillingIntroduction to Directional Drilling3. Directional Drilling Aplications

Relief WellsIntroduction to Directional Drilling3. Directional Drilling Aplications

Horizontal WellsIntroduction to Directional Drilling3. Directional Drilling Aplications

Extended Reach WellsIntroduction to Directional Drilling3. Directional Drilling Aplications

Multilateral WellsIntroduction to Directional Drilling3. Directional Drilling Aplications

Short, Medium, and Long Radius Wells