Prepared by
Y. MADI
The present document is devised for non
experienced engineers acting in drilling
field engineering.
The course is composed on sequences
related to drilling operations in order to
make hole, to stabilize the wall formations
and to keep under control oil wells.
As the completion of the program, the
engineers will be able to understand:
Well planning
Drill String
Casing design
Cementing job
Wellheads and BOP
Well Control
FOREWORD
WELL PLANNING
Geophysic Studies (Logging) Geology Studies Reserve Estimation
Well Implantation
Well Coordinates
Preparation of the Rig site
PRELIMINARY STUDIES
Well Planning is defined as the drilling program to
drill a well from the rig site to the target. This
program is also called "Architecture". It includes all
operations involved to build the well such as casing,
cementing, well control and safety.
Well Planner Engineers are responsible to elaborate
the drilling program taking into account the cost, the
duration with the respect of the environment.
To perform this task, they need to gather many
informations and work with a team composed by
Geologists, Log engineers, Reservoir engineers,
Production engineers, Drillers, Mud engineers
The main required data is the Lithology that shows
all formations to be drilled from the surface to the
target.
Based on this lithology, the team work is able to:
Identify the nature of formation (sand, clay, sandstone, dolomite.)
Estimate the thickness of layers Estimate the Dip of layers Detect weak zones Presence of undesirable fluids contained in the formation
Detect faults, anticlines..
WELL PLANNING
The total depth to reach the target is required to plan the well path.
The size of the tubing needed to produce the oil is very important data
given by the Production Department.
The drilling program permits to determine
:
The number of drilling sections
The depth of each section
The diameters of bits
The diameters of casings
The type and properties of the drilling
fluid
Based on the oilfield experience, the
drilling program is composed from 3 to 5
sections.
Exploration : sections
Development : 4 sections
WELL PLANNING
Ho
le D
epth
x 1
00
0 f
t
Mud Weight ppg
Casing Formations
CASING PROGRAM
Data
Lithology Total Depth Production diameter
Example : Drilling program
of 4 sections
How to elaborate Well Planning
Start from the last section where the production diameter is given
(known). This diameter is C4 (Casing diameter)
To drill the section, the drilling bit
diameter is D4 (Drilling diameter)
J1 J1
4th Section
Clearance
D4
C4
Clearance
J1 : Clearance between the bit
diameter and the outside diameter
casing in the same section.
This clearance vary from 11/2 to 4"
J2 : Clearance between the inside
diameter casing and the bit diameter
for the next section. The minimum
clearance may be :
1/8 " casings 41/2 to 85/8
5/32 " casings 95/8 to 133/8
3/16 " casings 16" to 20"
D4 = C4 + 2 J1
3rd Section :
ic3 = D4 + 2 J2 where :
ic3 inside diameter casing
ec3 = ic3 + 2 e where
e : outside diameter casing
and
e : wall thickness of the
casing
D4= ec3 + 2 J1
J1 J1
J2 J2
4th Section
3rd Section
2nd Section :
iC2 = D3 + 2 J2
eC2 = iC2 + 2 e
D2 = eC2 + 2 J1
J1 J1
J1
J1
J1
J1
J2 J2
J2 J2
4th
section
3rd
section
2nd
section
1st section :
iC1 = D2 + 2 J2
eC1 = iC1 + 2 e
D1 = eC1 + 2 J1
Well Planning
Drilling Casing Depth (ft)
26" 185/8 1200
16" 133/8 4500
121/4 95/8 8700
81/2 7'' 13500
6" 41/2 15200
Example of Well
Planning
18"5/8 Casing shoe @ 464m
26" Hole @ 465m
13 3/8 " Casing Shoe @ 2392m
16" Hole @ 2393m
9 5/8 " Casing Shoe @ 3345m 121/4" Hole @ 3346m
7" Casing Shoe @ 3404m K.O.P @ 3060m
8 3/8" Hole @ 3405m
6" O-Hole
Drilling / Casing Program
Surface Casing
Intermediate
Casing
Intermediate
Casing
Production
Casing
Drilling Casing Cement
Top Related