Drilling and Completion of Multilateral Wells

MULTILATERAL 

TERMINOLOGIES 

—Laterals are wellbores drilled from the main wellbore. 

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— Wellbores drilled from a horizontal lateral into the horizontal plane  are branches, those drilled from horizontal lateral into the vertical plane are splays.

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—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.

—SRS is the solution for increasing
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.

—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.

— 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 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.

—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.

—In these cases, pressure integrity is necessary to prevent junction collapse, due to pressure drawdown.

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—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.

—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

watch video

http://oiltube.blogspot.com/2012/03/drilling-and-completion-of-multilateral.html