MULTILATERAL
TERMINOLOGIES
—Laterals are wellbores
drilled from the main wellbore.
—
— Wellbores drilled
from a horizontal lateral into the horizontal plane are branches, those drilled from
horizontal lateral into the vertical plane are splays.
—
—A multilateral well
can follow different well trajectories: horizontal or
deviated Junctions
are the intersections of the laterals with the main wellbore or of the branches
and splays with the lateral
Multilateral Completion Systems
—Sperry-Sun drilling
Services Company has developed two distinct completion systems for multilateral
well bores which have full-open through-bore and re-entry capabilities. These
systems are:
—Lateral-Tie
Back System, LTBS.
—Retrievable
Multi-Lateral System, RMLS.
—British Petroleum Co.
(BP), has another system that is called "SRS", Selective
Re-entry System
for existing casing.
—This system was
developed by Weatherford Services Co.
The Lateral-Tie Back System, LTBS
This system consists
of six main components
1.Pre-milled casing
window joint.
2.drilling whipstock..
3.Lateral liner hanger.
4.Lateral liner running
tool.
5.Cementing whipstock if drill with
cemented Junctions.
6.Re-entry whipstock.
Retrievable Multi-Lateral System, RMLS
The RMLS consists of
four components
1.Casing window system.
2.Retrievable
deflection tool (whipstock) incorporating.
3.Lateral liner
transition joint.
4.Washover assembly.
Selective Re-entry System of
Multilaterals
—Technologies were not
developed that enabled drilling
multilaterals into different producing reservoirs.
multilaterals into different producing reservoirs.
—SRS is the solution
for increasing
oil production and reserves
from existing wells.
oil production and reserves
from existing wells.
Technology Advancement Multilateral (TAML)
—Classified
multilateral wells into seven categories (six levels with one
sublevel)
and provided a common language for operators and service companies to use when
discussing multilateral completions.
—The definitions of
the TAML levels were based on the amount and type
of support and functionality provided at the junction in the well where
one lateral wellbore merges with the main bore or with another lateral.
Technology Advancement of Multilaterals (TAML) levels
—Level 1:
is an open-hole lateral from an openhole mother bore.
is an open-hole lateral from an openhole mother bore.
—There is no
mechanical or hydraulic junction involved.
—Carried out in
consolidated formation as barefoot completions.
—widely applied in the
United States, Canada, Europe, and the Middle East, with up to six lateral
having been drilled from mother bore.
—Level 2:
main bore is cased in cemented and the lateral bore is open.
main bore is cased in cemented and the lateral bore is open.
— The completion is
economical, allows selective production, and can be carried out in standard
casing sizes.
— United Arab Emirates
wells have proven successful candidates for level 2.
—Level 3:
the main bore is cased and cemented, and the laterals are cased but not cemented.
the main bore is cased and cemented, and the laterals are cased but not cemented.
—The lateral liner is
mechanically anchored to the main bore using a liner hanger.
—level 4:
both the main bore and laterals are cased and cemented to provide mechanical junction integrity.
both the main bore and laterals are cased and cemented to provide mechanical junction integrity.
—can be simple, or
they can be the basis for more complex systems such as dual packers
completions, single string selective reentries and single strings with lateral
entry nipples.
—Level 5
Sealed junctions multilaterals
are necessary for reservoir management
and to handle complex geology in well
environments with multiple pressures,
fluids, and the rock strata.
Sealed junctions multilaterals
are necessary for reservoir management
and to handle complex geology in well
environments with multiple pressures,
fluids, and the rock strata.
—In these cases,
pressure integrity is necessary to prevent junction collapse, due to pressure
drawdown.
—
—Full hydraulic and
mechanical pressure integrity at junction are achieved with completion.
—Level 6:
one in which junction pressure integrity is achieved with the casing and not by cement, which is not acceptable.
one in which junction pressure integrity is achieved with the casing and not by cement, which is not acceptable.
—The entire junction
is an integral part of the main bore casing string.
—The first and most
widely used level 6 system is the formation junction
system.
—The system is run in
a perforated mode as part of a standard casing or liner string, then reformed
down hole using swaging technology.
—Conventional
drilling, completion, and cementing techniques are used to finish construction
and completion of well bore
