US 6,047,774 A · System for drilling and completing multilateral wells

Abstract

The time required for establishing a multilateral well is reduced by enlarging a section of a wellbore and running a multilateral tool into the enlarged wellbore section. The multilateral tool, which is suitable for running into a wellbore on a primary casing string, includes a preassembled combination of casing sections that are used to form dual casings strings extending from the primary casing. The multilateral tool incorporates three casing sections, which maintain the diameter of the primary casing, including: a carrier section, a lateral section, and a main section. In use, the tool is run with the lateral section releasably held in coaxial alignment within the carrier section, and with the main casing section fixed to the lower end of the carrier section. Once in place in the enlarged section of the wellbore, the lateral section is released and diverted out of a preformed window in the lower end of the carrier section and runs generally parallel to the main casing section. In this manner a lateral junction is formed at the carrier casing window in which dual casing strings are connected to the primary casing. A second window, which is preformed in the upper end of the lateral section is aligned with the bore of the primary casing when the lateral casing section is fully extended out of the carrier section window, thus permitting recovery of a diverting device incorporated in the carrier casing section through the second window. The dual strings are then individually drilled and completed to target locations with pressure integrity between the dual strings maintained by using straddle equipment across the lateral junction.

Claims17

Dependent claims

A multilateral tool for reducing the time required for drilling and completing a multilateral well, said multilateral tool comprising:

(a) a main casing section:
(b) a carrier casing section having a first end coaxially connectable to a primary casing and a second end connectable to said main casing section, and having a first preformed window near said second end thereof;
(c) a lateral casing section having a first end and a second end, and having a second preformed window near said first end thereof;
(d) wherein said carrier casing section is adapted for closely receiving said lateral section coaxially, with said first end of said carrier casing section being adjacent to said first end of said lateral casing section when said lateral casing section is received in said carrier casing section and
(e) means for releasably holding said lateral casing section within said carrier casing section;
(f) diverting means positioned in said second end of said carrier casing section for diverting said lateral casing section through said first preformed window when said lateral casing section is advanced toward said second end of said carrier casing section;
and
(g) wherein said carrier casing section and said primary casing section are coaxially aligned and said second preformed window is aligned with the bore of said primary casing when said lateral casing section is fully extended through said first preformed window, thereby permitting recovery of said diverting means through said second preformed window.

5 more elements

Apparatus for providing pressure integrity in a multilateral well, said apparatus comprising:

(a) a multilateral tool connected to a primary casing in a wellbore, wherein said multilateral tool includes a lateral junction providing an unsealed connection of at least a first and a second casing string to said primary casing;
(b) a first intermediate liner casing section extending said first casing string into a subterranean formation;
and
(c) a first scab tieback liner connecting the upper end of said first intermediate liner casing section to the lower end of said primary casing, so as to straddle said lateral junction in said multilateral tool and provide pressure integrity for said first casing string for further drilling in said first casing string.

1 more element

A method for establishing multilateral wells with pressure isolation between wells, wherein a single primary casing positioned in an enlarged wellbore section is expanded to form at least dual casing strings, said method comprising the steps of:

(a) running a multilateral tool connected to said primary casing into said enlarged wellbore section, wherein said multilateral tool includes a lateral junction providing an unsealed connection of at least a first and a second casing section to said primary casing to provide at least a first and second casing string;
(b) drilling a first hole for extending said first casing string;
(c) running and cementing a first intermediate liner section into said first hole, thereby extending said first casing string;
(d) providing a first scab tieback liner from the upper end of said first intermediate liner section to the lower end of said primary casing so as to straddle said lateral junction in said multilateral tool and thus provide pressure integrity for said first casing string;
and
(e) providing a first production liner extending from the lower end of said first intermediate liner in said first casing string.

3 more elements

Dependencies are inferred from the claim text.

System for drilling and completing multilateral wells

Life of this patent

System for drilling and completing multilateral wells

Life of this patent

Abstract

Claims17