MULTILATERAL
DRILLING
Group 5
1. Huda basim shakir
2. Asmaa hussein
3. Um albaneen ali
4. Sura abass
Multilateral well
is a well with two or more laterals
(horizontal, vertical, or deviated) drilled
from a main mother well. This allows one
well to produce from several reservoirs.
Multilateral wells are suitable for
complex geology where drilling more new
wells to penetrate to those reservoirs is
not economical. Lateral sections may be
used to produce from a separated section
in depleted, faulted, layered and heavy oil
reservoirs.
Background of Multilateral Wells
The first known multilateral well was drilled in Bashkiria, Russia, in 1949.(some references in 1953) by
Alexander Grigoryan9 , he is Consider the father of multilateral wells.
In 1949, he developed an interest in the theoretical work of American scientist L. Yuren ,
who maintained that increased production could be achieved by increasing the diameter of the borehole in
the productive zone of the formation. Since 1992, the use of ML drilling technology in the Middle East has
seen significant growth to the extent that Middle
East is one of the most active areas in the world for ML applications.
In 1996, it is estimated that over 35 MLs were drilled in the Middle East.
Advantages of ML Wells
The various advantages of multilateral wells can be summarized as follows:
1. Reduction in well costs. This is due to the need to use fewer top-side and near
surface equipment for a single multilateral well as compared to a group of
conventional wells.
2. Mechanically sealed junctions with full casing integrity eliminate one of the main
failure point as compared to other multilateral designs
3. Improves sweep efficiency by delaying gas or water breakthrough.
4. Facilitates better drainage of heterogeneous reservoir systems.
5. Enhances production for difficult fluids.
6. Reduction of environmental footprint.
7. Increases the reservoir exposure.
8. Better connects the natural reservoir permeability
9. Greater exposure accelerates the production rate.
10. Accelerated production also allows for early production of secondary or marginal
reserves.
11. Reduced overall project costs improving the rate of return.
drilling of multilateral wells involves certain risks
• 1- borehole instability
• 2-stuck pipe
• 3-problems with overpressured zones to casing,
• 4-cementing and branching problems.
• 5- a high risk of drilling or completion formation damage and difficulties locating and staying
• in the productive zone while drilling the laterals.
Multilateral Designs
Multilateral classifications
TAML Level 2
Main bore cased and
TAML Level 1 cemented Lateral bore open
Open / Unsupported junction
ADVANTAGES
ADVANTAGES • Permanent datum point in the well Multiple laterals
Simplest construction • Controlled re-entry
Stable in hard formations
DISADVANTAGES
DISADVANTAGES • Limited to new well applications Limited completion options
•Not stable in unconsolidated • No pressure integrity at the junction
formations
• Limited life due to hole collapse
•No positive re-entry capability
•Limited completion options
•Not pressure containing
TAML Levels 3 TAML Level 4
Main bore cased and cemented Lateral Both main bore and lateral bore
bore cased but NOT cemented cased and cement
ADVANTAGES ADVANTAGES
• New well and existing well applications • New well and existing well applications
• Permanent datum point in the well Permanent datum point in the well
Multiple laterals • Multiple laterals
• Positive re-entry • Positive re-entry
• Open hole support • Open hole support
• Adaptable to all formation types
DISADVANTAGES
• No pressure integrity at the junction DISADVANTAGES
• No pressure integrity at the junction
TAML Level5 TAML Level6
Pressure integrity at the junction achieved with Pressure integrity at the junction achieved with casing
completion equipment (Cement IS NOT Acceptable ) (Cement IS NOT Acceptable)
ADVANTAGES ADVANTAGES
• New well and remedial applications Permanent • Positive re-entry
datum point in the well Positive re-entry • Mechanical and hydraulic support
• Open hole support • Adaptable to all formation types Numerous
• Adaptable to all formation types completion options
DISADVANTAGES DISADVANTAGES
• Restricted re-entry access • Limited pressure differential ratings Larger well bore
requirements
Choosing a Lateral Design
The geometry of an ML well is determined by the production targets, their relative depths and lateral
extents. The laterals may be on the same horizontal plane at the same true vertical depth or they may
be on the same vertical plane and follow the same direction but at different depths. Within these two
main categories, a nearly infinite number of combinations can be created that may cover multiple
zones or span out in various directions within a single reservoir
Multilateral well with different geological structure
Multilateral Drivers
• Increased Reserves
Ø Access reserves whilst reducing well development costs
Ø Marginal reservoirs
Ø Stacked/ compartmentalized reservoirs
Where Can Multilaterals be used?
Ø Small pools
Ø Tight rock
Ø Stacked/ compartmentalized reservoirs
Ø Pools that are impossible to connect with one hole section
MRC (Maximum Reservoir Contact) and ERC (Extreme
Reservoir Contact)
