WO2002068795A1 - Procede d'injection de liquides destine a des colonnes montantes de forage - Google Patents

Procede d'injection de liquides destine a des colonnes montantes de forage Download PDF

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Publication number
WO2002068795A1
WO2002068795A1 PCT/US2002/005159 US0205159W WO02068795A1 WO 2002068795 A1 WO2002068795 A1 WO 2002068795A1 US 0205159 W US0205159 W US 0205159W WO 02068795 A1 WO02068795 A1 WO 02068795A1
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WO
WIPO (PCT)
Prior art keywords
low
drilling
density
liquid
density liquid
Prior art date
Application number
PCT/US2002/005159
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English (en)
Inventor
Charles Rapier Dawson
Yuh-Hwang Tsao
Sandra Nowland Hopko
Original Assignee
Exxonmobil Upstream Research Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Exxonmobil Upstream Research Company filed Critical Exxonmobil Upstream Research Company
Priority to GB0321638A priority Critical patent/GB2391572B/en
Priority to BRPI0207407-9A priority patent/BR0207407B1/pt
Priority to AU2002245482A priority patent/AU2002245482B2/en
Priority to MXPA03007387A priority patent/MXPA03007387A/es
Priority to CA002438885A priority patent/CA2438885C/fr
Publication of WO2002068795A1 publication Critical patent/WO2002068795A1/fr
Priority to NO20033720A priority patent/NO325188B1/no

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Classifications

    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/001Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor specially adapted for underwater drilling
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/08Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure
    • E21B21/085Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure

Definitions

  • the invention relates generally to offshore drilling systems. More particularly, the invention relates to a dual-gradient offshore drilling system using low-density liquid lift for drilling risers.
  • Deep water drilling typically involves the use of marine risers.
  • a riser is formed by joining sections of casing or pipe. The riser is deployed between the drilling vessel and wellhead equipment located on the sea floor and it is used to guide drill pipe and tubing to the wellhead and to conduct a drilling fluid and earth-cuttings from a subsea wellbore back to the floating vessel.
  • a drill string is enclosed within the riser pipe. The drill string includes a drilling assembly that carries a drill bit.
  • drilling mud A suitable drilling fluid (commonly called “drilling mud” or “mud”) is supplied or pumped under pressure from the drilling vessel. This drilling mud discharges at the bottom of the drill bit. Mud lubricates and cools the bit, and lifts drill cuttings out of the wellbore.
  • drilling mud is circulated down the drill string and up through an annulus between the drill string and the wellbore below the mudline (sea floor), and from the mudline to the surface through the riser/drill string annulus.
  • Drilling mud is very important in the drilling process. It serves as: (1) a lubrication and heat transfer agent; (2) a medium to carry away and dislodge pieces of the formation cut by the drill bit; and (3) a fluid seal for crucial well control purposes.
  • drilling operators attempt to carefully control the mud density at the surface of the well to avoid many potential problems.
  • One potential problem is "lost circulation" when a column of drilling mud exerts excess hydrostatic pressure, which propagates a fracture in the formation. Formation fluids may enter the wellbore unexpectedly when the hydrostatic pressure falls below the formation pressure. Such an event is called “taking a kick.” A blowout occurs when the formation fluid enters the wellbore in an uncontrolled manner. Both of these problems become even more difficult to overcome in deep water.
  • ECD equivalent circulating density
  • Dual-gradient drilling is an area of technology that is primarily used to overcome the narrow pore pressure/fracture gradient margins found in abnormally pressured, ultra- deepwater wells.
  • dual-gradient drilling permits drilling in deep and ultra deep water using fewer casing strings than possible using conventional drilling systems. Because there are fewer casing strings used, there is potential for drilling dual-gradient wells faster than conventionally drilled wells. Dual-gradient drilling can also enhance extended-reach drilling by reducing the influence of circulating pressure losses on bottom-hole pressure.
  • Dual-gradient drilling can be used to drill a wellbore with a larger diameter hole at the bottom of the wellbore, resulting in lower pressure drop per unit length than a smaller diameter wellbore.
  • Forms of dual-gradient drilling technology being developed include pump- lifted and gas-lifted drilling risers.
  • Pump-lift systems use pumps positioned near the sea floor to pump the heavy mud/drilling returns from the mud line to the drilling vessel to reduce the hydrostatic pressure at the mud line, generally to that which would result from a sea water gradient.
  • Illustrative of the pump-lift systems is U.S.
  • Patent 4,813,495 to Leach that discloses a method and apparatus for drilling subsea wells in water depths exceeding 3000 feet (915 meters) (preferably exceeding 4000 feet (1220 meters)) where drilling mud returns are taken at the seafloor and pumped to the surface by a centrifugal pump that is powered by a seawater driven turbine. See also U.S. Patent No. 4,149,603 to Arnold and published PCT application WO9915758. Limitations with the pump-lift systems include wear and equipment reliability for the subsea pumps and motors. Also, the ability of the pump-lift system to handle dissolved and entrained gas is potentially very poor.
  • U.S. Patent No. 4,099,583 to Maus discloses an offshore drilling method and apparatus which are useful in preventing formation fracture caused by excessive hydrostatic pressure of the drilling fluid in a drilling riser.
  • One or more flow lines are used to withdraw drilling fluid from the upper portion of the riser pipe. Gas injected into the flow lines substantially reduces the density of the drilling fluid and helps provide the lift necessary to return the drilling fluid to the surface.
  • the rate of gas injection and drilling fluid withdrawal can be controlled to maintain the hydrostatic pressure of the drilling fluid remaining in the riser and wellbore below the fracture pressure of the formation. See also U.S. Patent No.
  • the invention is a method of drilling a well below a body of water using a drill string that starts by injecting into the well, at a depth below the water surface, a liquid having a lower density than a density of a drilling mud. This produces a mixture of drilling mud and low-density liquid in the well.
  • the low- density liquid may be miscible or immiscible with the drilling mud.
  • the mixture of drilling mud and low-density liquid is withdrawn from an upper end of the well.
  • At least a portion of the low-density liquid is separated from the mixture of drilling mud and low-density liquid, with at least a portion of the separated low-density liquid returned to the depth below the water surface and at least a portion of the drilling mud depleted of low-density liquid being returned to an upper end of the drill string.
  • An embodiment of the invention includes controlling the injection rate of the liquid.
  • the rate of the liquid injected can be selected so the cuttings within the riser pipe have an upward velocity in excess of the settling rate of the cuttings in the riser pipe.
  • the rate of the liquid injected can be selected so the liquid lift maintains a bottom-hole pressure that is below the fracture pressure of the earth formation and above the pore pressure of the formation.
  • Figure 1 illustrates an offshore drilling system configured for dual gradient riser drilling.
  • Figure 2 illustrates a liquid lift system for drilling risers in accordance with one embodiment of the present invention.
  • Figure 3 illustrates mud processing in a liquid lift system for drilling risers in accordance with one embodiment of the present invention.
  • Figure 4 depicts a flowchart of miscible liquid lift in accordance with one embodiment of the present invention.
  • Figure 5 depicts a flowchart of immiscible liquid lift in accordance with one embodiment of the present invention.
  • Fig. 1 illustrates one type of offshore drilling system (10) where a drilling vessel (12) floats on a body of water (14) which overlays a pre-selected earth formation (17A).
  • a drilling rig (20) is positioned in the middle of the drilling vessel (12), above a moon pool (22).
  • the moon pool (22) is a walled opening that extends through the drilling vessel (12) and through which drilling tools are lowered from the drilling vessel (12) to the sea floor or mudline (17).
  • a structural pipe (32) extends into a wellbore (30).
  • a conductor housing (33) is attached to the upper end of the conductor pipe (32).
  • a guide structure (34) is installed around the conductor housing (33) and adjacent a blowout preventor (38) before the conductor housing (33) is run to the mudline (17).
  • a wellhead (35) is attached to the upper end of a conductor pipe (36) that extends through the structural pipe (32) into the wellbore (30).
  • the wellhead (35) is of conventional design and provides a facility for hanging additional casing strings in the wellbore (30).
  • a riser system like the one depicted in Fig. 1 typically includes one or more auxiliary lines (well-control lines 53 and boost line 68) on the outside of a riser (52).
  • Well control lines (53) provide a high-pressure conduit for fluid flow between a BOP (38) and a drilling rig (20).
  • a boost line (68) supplies drilling fluid to the bottom of a riser (52) to enhance the removal of drill cuttings.
  • a drill string (60) extends from a derrick (62) on the drilling rig (20) into the wellbore (30) through a riser (52) which extends generally from the blowout preventor (38) back to the drilling vessel (12).
  • Attached to the end of the drill string (60) is a bottom hole assembly (63), which typically includes a drill bit (64) and one or more drill collars (65).
  • the bottom hole assembly (63) may also include stabilizers, mud motor, and other selected components required to drill a wellbore (30) along a planned trajectory, as is well known in the art.
  • the end result is the creation of a well that extends from above the water surface to below the mudline (17) into the earth formation (17 A).
  • drilling mud is pumped down the bore of the drill string (60) by a surface pump (not shown) and is forced out of the nozzles (not shown) of the drill bit (64) into the bottom of the wellbore (30).
  • Cuttings resulting from the drilling become entrained in the mud at the bottom of the wellbore (30) and the mud laden with cuttings rises up the wellbore annulus (66) and into the riser/drill string annulus (54 in Fig. 3), and to the surface for treatment in mud cleaning facilities (not shown).
  • the passage of the mud from the bottom of the wellbore to the surface of the body of water may be referred to as a return flow system.
  • the return flow system may comprise a first annular space between the drill string (60) and the wall of the wellbore (30), and a second annular space between the drill string (60) and the inner surface of casing (36) positioned in the wellbore, and a third annular space between the drill string (60) and the riser (52) extending between the cased wellbore and the surface of the body of water (14).
  • a liquid-lift drilling riser system uses a lightweight miscible or immiscible fluid to reduce the density of a drilling mud to as low as that of seawater.
  • a surface pump (not shown) pumps a low-density liquid (74) through a riser boost line (68).
  • the low-density liquid (74) is directed to the riser (52) approximately at the mud line (17) via the riser boost line (68).
  • the low-density liquid (74) will mix with the high-density mud (76) returning from the bottom of the well. This mixture (80) will retum to the surface and flow over shale shakers (not shown).
  • the mixture (80) will be separated and treated into its original low-density liquid (74) and high-density mud (76) components.
  • the high-density mud (76) (preferably substantially all of the high-density mud which is depleted of low-density liquid 21) will again be pumped down the drill string (60) and the low-density liquid (74) (preferably substantially all of the separated low-density liquid 74) will again be pumped down the riser boost line (68) back to the bottom of the riser (52).
  • Proper separation provides a closed loop system with low fluid losses.
  • Fig. 3 shows an alternative configuration for a liquid lift drilling system.
  • a lightweight miscible or immiscible fluid is used to reduce the density of a drilling mud to as low as that of seawater.
  • a surface pump (not shown) pumps a low-density liquid (74) through a fluid injection line (72).
  • the low-density liquid (74) is directed to a position below the mud line (17) via a parasite string (71) installed in the cased wellbore (37).
  • the parasite string thereby placing the low-density liquid 74 in an annular space between the drilling string 60 and the inner wall of casing 36 .
  • the low-density liquid (74) will mix with the high-density mud (76) returning from the bottom of the well.
  • This mixture (80) will return to the surface and flow over shale shakers (not shown). Once through the shale shakers (not shown), the mixture (80) will be substantially separated and treated into its original low-density liquid (74) and high-density mud (76) components. The high-density mud (76) will again be pumped down the drill string (60) and the low-density liquid (74) will again be pumped down the fluid injection line (68) through the parasite string (71) to the cased wellbore (37).
  • a miscible liquid-lift system uses a miscible liquid such as seawater to be injected into a water-based mud.
  • seawater is injected into the riser boost line (68) to dilute the mud, effectively reducing mud density (weight).
  • a portion of a return fluid is discarded at surface, and the water-based drilling mud is rebuilt with necessary additives needed to regain the desired mud weight.
  • the miscible liquid-lift system can comprise a base fluid common to both the low-density liquid (74) and the high-density mud (76).
  • the high-density mud (76) generally contains barite, hematite and/or other suitable weighting agents and is directed down the drill string (60) as previously explained.
  • the low-density liquid (74) may contain one or more density-reducing agents, such as low-density particulate materials, including, for example, hollow glass beads/microspheres or other density-reducing additive.
  • the low-density liquid (74) is directed to the riser (52) at the mud line (17) via the riser boost line (68 in Fig. 2), or is directed into the wellbore (37 in Fig. 3) via a parasite string (71 in Fig. 3).
  • the fluid mixture (80) returning up the riser pipe (52) contains both weighting agents and weight-reducing agents (if any).
  • drill solids are removed from the return fluid mixture (80) using one or more standard rig solids control devices (116).
  • the resulting fluid (82) then travels to one or more separation devices (112), such as mechanical separators, gravity separators, centrifuges, or other similar equipment.
  • the one or more separation devices (112) separate the fluid (82) into the low-density liquid (74) and weighting agent (114).
  • the low-density liquid (74) is moved to mud pits (110) before being redirected into the riser annulus (54 in Fig. 2) above the BOP (38 in Fig. 2) or into wellbore annulus (37 in Fig. 3) below the mud line (17 in Fig. 3).
  • the high- density mud (76) is re- formulated at (106) by combining the weighting agent (114) and a portion (83) of unprocessed fluid (82). Then, the re-formulated high-density mud (76) may be moved to mud pits (111) for temporary storage before being redirected into the wellbore (30 in Fig. 2).
  • the miscible liquid-lift system can be used for any type of drilling fluid, and this embodiment of the liquid-lift system can be used to drill part or all of the well.
  • an immiscible system uses a low-density boost liquid (74) that is substantially immiscible with the high-density mud (76) to lighten the returning drill fluid.
  • a low-density boost liquid (74) that is substantially immiscible with the high-density mud (76) to lighten the returning drill fluid.
  • An example of this is to drill with a weighted water-based mud and boost with a lightweight, immiscible synthetic fluid, such as an ester, olefin or glycol.
  • the low- density liquid (74) is introduced into the returning drill fluid at the base of the riser (52 in Fig. 2) or down the fluid injection string (72 in Fig. 3) or both the base of the riser (52 in Fig. 2) and down the injection string (72 in Fig. 3) simultaneously.
  • the resulting fluid (80) is a stable, two-phase fluid of lower density than the mud (76).
  • one or more conventional separation devices such as a three- phase centrifuge, can be used to separate the fluid mixture (80) on the drilling vessel (12 in Fig. 1), where the fluids (74, 76) can be re-circulated.
  • the fluid mixture (80) can be processed using standard solids control equipment (120), such as course- screen shakers, to remove part or substantially all of the drill solids.
  • the resulting fluid (82) is separated in oil-water separator (81), such as a three-phase centrifuge, to produce drill solids (86), low-density liquid (74), and drill fluid (122).
  • the drill solids (86) may be discarded in any environmentally suitable manner.
  • the low-density liquid (74) may be moved to mud pits (110) for temporary storage.
  • the drilling fluid (122) in this embodiment may pass through additional standard rig solids control devices (116), and then moved to mud pits (111) for temporary storage as high-density mud (76).
  • liquid lift system uses a combination fluid, such as low-density glass beads (or a density-reducing agent) in a miscible low-density liquid slurry.
  • a combination fluid such as low-density glass beads (or a density-reducing agent) in a miscible low-density liquid slurry.
  • miscible low-density liquid slurry instead of the low-density mud without the slurry
  • the density-reducing agent may be recovered at the surface before discarding the excess volume of fluid, if any. The result is a stable, homogeneous fluid of lower density than the mud pumped down the drill string (60 in Fig. 1).
  • controlling the rate of the low-density liquid (74) injected into the riser (52) at or near the mud line (17) via the riser boost line (68), or directed into the cased wellbore (37 in Fig. 3) via the fluid injection string (72 in Fig. 3) has two primary purposes in the liquid-lift system.
  • the rate of the liquid injected can be controlled so the cuttings within the riser pipe annulus (54) have an upward velocity in excess of the settling rate of the cuttings in the riser pipe (52).
  • the rate of the low-density liquid (74) injected can be controlled to maintain a bottom- hole pressure that is below the fracture pressure of the earth formation and above the pore pressure of the formation.
  • the liquid-lift system has several advantages over pump-lift and gas-lift systems.
  • the liquid-lift system can use conventional solids control equipment and rig pumps to produce a simpler, more reliable dual-gradient drilling system than a pump- lift system.
  • Cuttings transport is conventional
  • kick detection is conventional
  • circulation can be stopped (remain static) without adverse consequences, and there is little or no additional subsea equipment to break down, thereby creating a need for a riser trip to repair.
  • the liquid-lift system also allows the switching of drilling from dual-gradient to conventional, single- gradient merely by ceasing the injection of the low-density boost fluid to the riser (52 in Fig. 2).
  • the liquid-lift system also allows for additional injection/lift points than just the mud line.
  • the use of a parasite string (71 in Fig. 3) to inject lift fluid below the mud line (17 in Fig. 3) increases the effectiveness of the liquid-lift system and provides incentive for use of dual-gradient drilling in shallow water or on land. Additionally, by using the parasite string to inject the lift fluid below the mudline (17 in Fig. 3), the volume of lift fluid necessary to create lift in the riser (52 in Fig. 3) can be reduced.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
  • Gas Separation By Absorption (AREA)

Abstract

L'invention concerne un procédé de forage d'un puits au-dessous des eaux consistant à injecter dans ce puits, à une certaine profondeur au-dessous de la surface de l'eau, un liquide (74) possédant une densité inférieure à la densité d'une boue de forage (76) permettant de produire un mélange de boue de forage (76) avec un liquide de faible densité (74) dans le puits. Le mélange de la boue de forage (76) avec le liquide de faible densité (74) est retiré de l'extrémité supérieure du puits. La boue de forage (76) et le liquide de faible densité (74) sont séparés, au moins une partie du liquide de faible densité (74) séparé étant rejetée au-dessous de la surface de l'eau et au moins une partie de la boue de forage séparée (76) étant rejetée dans l'extrémité supérieure du train de forage (60).
PCT/US2002/005159 2001-02-23 2002-02-21 Procede d'injection de liquides destine a des colonnes montantes de forage WO2002068795A1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
GB0321638A GB2391572B (en) 2001-02-23 2002-02-21 Liquid lift method for drilling risers
BRPI0207407-9A BR0207407B1 (pt) 2001-02-23 2002-02-21 método de perfuração de um poço abaixo de um corpo de água, no qual uma broca de perfuração é girada na extremidade de uma coluna de perfuração e método de tratamento de um fluido de perfuração usado na perfuração de um furo de poço em uma formação do terreno abaixo de um corpo de água.
AU2002245482A AU2002245482B2 (en) 2001-02-23 2002-02-21 Liquid lift method for drilling risers
MXPA03007387A MXPA03007387A (es) 2001-02-23 2002-02-21 Metodo de elevacion de liquido para tubos ascendentes de perforacion.
CA002438885A CA2438885C (fr) 2001-02-23 2002-02-21 Procede d'injection de liquides destine a des colonnes montantes de forage
NO20033720A NO325188B1 (no) 2001-02-23 2003-08-21 Fremgangsmate for vaeskeloft i borestigeror

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US27130401P 2001-02-23 2001-02-23
US60/271,304 2001-02-23

Publications (1)

Publication Number Publication Date
WO2002068795A1 true WO2002068795A1 (fr) 2002-09-06

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ID=23035014

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2002/005159 WO2002068795A1 (fr) 2001-02-23 2002-02-21 Procede d'injection de liquides destine a des colonnes montantes de forage

Country Status (8)

Country Link
AU (1) AU2002245482B2 (fr)
BR (1) BR0207407B1 (fr)
CA (1) CA2438885C (fr)
GB (1) GB2391572B (fr)
MX (1) MXPA03007387A (fr)
NO (1) NO325188B1 (fr)
OA (1) OA12493A (fr)
WO (1) WO2002068795A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955411A (en) * 1974-05-10 1976-05-11 Exxon Production Research Company Method for measuring the vertical height and/or density of drilling fluid columns
US6197095B1 (en) * 1999-02-16 2001-03-06 John C. Ditria Subsea multiphase fluid separating system and method
US6277286B1 (en) * 1997-03-19 2001-08-21 Norsk Hydro Asa Method and device for the separation of a fluid in a well
US6328107B1 (en) * 1999-09-17 2001-12-11 Exxonmobil Upstream Research Company Method for installing a well casing into a subsea well being drilled with a dual density drilling system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955411A (en) * 1974-05-10 1976-05-11 Exxon Production Research Company Method for measuring the vertical height and/or density of drilling fluid columns
US6277286B1 (en) * 1997-03-19 2001-08-21 Norsk Hydro Asa Method and device for the separation of a fluid in a well
US6197095B1 (en) * 1999-02-16 2001-03-06 John C. Ditria Subsea multiphase fluid separating system and method
US6328107B1 (en) * 1999-09-17 2001-12-11 Exxonmobil Upstream Research Company Method for installing a well casing into a subsea well being drilled with a dual density drilling system

Also Published As

Publication number Publication date
CA2438885C (fr) 2010-01-19
NO20033720D0 (no) 2003-08-21
GB2391572B (en) 2005-02-02
CA2438885A1 (fr) 2002-09-06
BR0207407A (pt) 2005-04-12
GB0321638D0 (en) 2003-10-15
AU2002245482B2 (en) 2006-06-29
MXPA03007387A (es) 2003-12-04
OA12493A (en) 2006-05-24
NO20033720L (no) 2003-08-21
BR0207407B1 (pt) 2011-09-06
NO325188B1 (no) 2008-02-11
GB2391572A (en) 2004-02-11

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