Sonatrach Directional Drilling

INTRODUCTION TO HYDROCARBON EXPLOITATION Development Phase

Introduction to Hydrocarbon Exploitation Directional Drilling Section By Pratap Thimaiah

©2005 Abalt Solutions Limited. All rights reserved

Deviated Holes 

g n i l l i r D l a n o i t c e r i D y g o l o n h c e T g n i l l i r D

The Reasons Reasons for Directional Directional Drilling: Drilling: – Side tracking existing wells – Restricted surface locations – Reaching Multiple targets – Reduction in number of offshore platforms – Horizontal drilling – Thin reservoirs – Environmental foot print – Avoiding salt domes – Geological requirements – To avoid gas and water conning – Intersecting fractures – Re-entry of existing wells


©abalt solutions limited - 2005

September – October 2005


Applications

g n i l l i r D l a n o i t c e r i D y g o l o n h c e T g n i l i r D


Directional Well Planning 

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Specifica Spec ification tion of Target, Size & Shape Shape.. Rig Location Location Loca tion of Adjacent Wells Wells Casing Casi ng and mud Programmes Programmes





Co-ordinate systems 

Geographic Co-ordinates Co-ordinates (Figure 11.1 pg 376Rabia) They are an imaginary network of lines superimposed on the globe


– Latitude (degrees north or south of Datum plane) – Longitude (degrees east or west of Datum plane)


Co-ordinate systems 


UTM (Universal Transverse Mercator) Mercator) (Figure 11.6 pg 382-Rabia) – Grid used to cover the world except for the polar regions. – Based Based on 60 zones, zones, each each is 6 deg degree rees s of longitude wide ad extends from 80 degree S to 84 degree N latitude . – Meters is the unit of measurement. – Greenwich meridian is chosen as the zero degree reference meridian.





Reference directions 

There Ther e are 3 azim azimuth uth reference reference systemssystems– True Geographic north – Grid north – Magnetic north



Geographic North 

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It is ref referr erred ed to as true north north or a tru true e azi azimut muth. h. Geographic Geographi c north points to the north pole and indicated by the polar star. By conven conventio tion n it is referre referred d to as a sta starr on UTM grid





Well Profiles 

Having fixed target and location Having location of well rig, next is to plan geometrical profile of well to reach target.



Well Profiles






Well Profiles



Deflection Tools 

Badgerr Bit (Jet Deflectio Badge Deflection) n) – Usin Using g full fluid power directed directed through through one enlarged enlarged nozzle of b it.


– Bit lowered lowered into assembly assembly with a non magnetic magnetic drill collar and stabilizer – Orie Oriented nted bit with Enlarged Enlarged nozzle nozzle is poin pointed ted in requ required ired direction. direction. – By pumping pumping through the bit while while the string is rotated-washed rotated-washed pocket – Continuo Continuous us jetting jetting working working on pipe. – Used mai mainly nly in soft soft formations formations..






Whip stock– Stee Steell wedge run run in the hole and set set at KOP.

– Standard removable used removable used for side tracking and kick off wells. – Permanent Permanent whipstock whipstock is designed to remain permanently in hole. To bypass junk or collapsed casing





Rebel Tool – Designed Designed to to give bit push push either either push to left or right. – Too Tooll body has has a groove groove cut along along its length inside which is a torsion bar. – Rod is free free to rotate rotate and has a curved curved paddle connected on either end. – Paddl Paddles es pivot in the the milled milled recesses recesses in tool body. – When the the top paddle paddle rotates rotates to to low side of hole, it is forced into its recess. – Inw Inward ard forc force e on top paddl paddle e is transmitted through torsion rod and causes caus es an outward force on botto bottom m paddle. – Bottom paddle paddle then then projects projects laterally laterally against the formation.





Deflection Tools Rebel Tool 

Advantages – Mak Makes es gradual gradual changes changes in direction direction – Allows Allows normal normal rotary drillin drilling g – Chea Cheaper per than downhol downhole e motors



Deflection Tools-PDM 

Positive Displacement Motor – Down Downhole hole mud motor motor .


– Drives Drives Bit without without rotating rotating the entire drill string. – Powered Powered by using drilling drilling fluid, fluid, air or gas.





Deflection Tools-PDM Components 

Dump Valve – By pass valve valve that allows allows the drill string string to fill up or drain when tripping.


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Motor Assembly – consists consists of lined stator stator which contains contains a spirally spirally shaped cavity cavity or elliptical section. – Soli Solid d steel steel spiral spiral shaft. shaft. – Top end is free, free, lower end end fixed to connecti connecting ng rod.

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Connecting rod – Equi Equipped pped with with universal universal joint joint at each end – Acc Accommoda ommodates tes eccentric eccentric rotation rotation of rotor and transfers transfers to drive shaft.

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Bearing Assembly – Consists Consists of thrust thrust & radial bearings bearings to allow smooth smooth rotation – Driv Drive e shaft is is connected connected to bit bit sub



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Some PDMs PDMs are multistage motors. Drilling fluid is is pumped pumped through the motor and forced between rotor & stator cavity. Rotation transferred by drive shaft to the bit. To deviate deviate a well, well, a bent bent sub must be run above the PDM. Above the bent Above bent sub sub an orienting device such as steering tool or MWD is accommodated






Bent sub – Short Short length length or collar sized sized pipe pipe – Axis of lower lower connectio connection n is slightly slightly offset from vertical – Sizes of of 1 to 3 degrees degrees are commo common. n.


Advantages using PDM – – – –

accurate accurat e control over over deviation deviation Less Les s risk risk of dog dog legs legs Can be used used to build build or drop drop angles angles Can be designe designed d to operate operate in high high solids or with LCM.


Deflection Tools-Turbo Drills 

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Type of of mud motor motor which which turns bit without drill string rotation. Can be powered by liquid liquid drilling fluids. Bladed rotors & stators stators mounted at right angles to fluid flow. Rotors attached attached to drive drive shaft, while stators to outer case. Rotor-stator Rotorstator pair is called called stage. There are 75 to 250 stages typically.

Advantages – Used for straigh straightt hole sections also. – Casi Casing ng wear wear reduced reduced – Low torque torque appl applied ied – Bett Better er penetrat penetration ion rates rates Disadvantage – Roto Rotorr prone to damage damage with mud debris ©2005 Abalt Solutions Limited. All rights reserved




Bottom Hole Assembly 

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BHA refers to combination combination of collar collars, s, stabilizers stabilizers and other tools run above bit. BHA designed designed to build, drop drop or hold.



Bottom Hole Assembly 

Packed Hole Assembly – DC and stabilizers stabilizers so positioned positioned to reduce bending bending and keep bit straight. – Botto Bottom m stand is made made as stiff stiff as possible. possible. – Shor Shortt DC and reamers reamers or stabilise stabilisers rs used

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Pendulum Assembly – Unsupporte Unsupported d weight of DC to force force the bit against against low side side of hole. – Resul Resulting ting decrease decrease or drop off in angle depends depends on WOB, rpm, stabilization stabilization – To increas increase e tendency tendency to drop: drop:   

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Apply less less WOB More pump pressure pressure in soft formations Use bigger Monel DC below reamer reamer and smaller DC above.

Fulcrum Assembly – Always Always run run a reamer reamer near near bit – When WOB WOB is applied, the DCs above above reamer reamer will tend to bend against against low side of hole, making reamer act as a fulcrum ,forcing the bit upwards. – Rate of build-up build-up depends upon WOB,siz WOB,size e of collars, position position of reamer and stabilization above reamer. – To incr increase ease build:   

More WOB Smaller size size Monel Less rpm and pump rates in soft formations formations




Sonatrach Directional Drilling

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