FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
THE PATENTS RULES, 2003
Provisional/ Complete specification
[See section 10 and rule 13]
1. Title of invention:
"Slim-hole gas lift completion with macaroni tubing carried gas lift valves."
2. Applicant(s):
Name Nationality Address
Oil and Natural Gas India IOGPT, Phase -II, Panvel -
Corporation Ltd. 410221, Navi Mumbai,
Maharashtra, India.
3. Preamble to the description:
The following specification particularly describes the invention and the manner in which it is to be performed.

SLIM-HOLE GAS LIFT COMPLETION WITH MACARONI TUBING CARRIED GAS LIFT VALVES
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method to isolate the damaged casing with a packer and to use the tubing string as the new casing for the macaroni tubing and to carry the gas lift valves inside the macaroni tubing. This innovative macaroni tubing carried slim hole gas lift valve completion provides flexibility to guard against future tubing pressure fluctuations due to changes in well operating conditions, help in reactivation / unloading of the well, if need be which is not possible with an open end macaroni tubing completion inside the normal production tubing isolating the damaged casing with a packer.
2. Description of the Prior Art:
Gas lift applications have the minimum requirement that the casing is hermetically intact. If a damaged casing occurs at shallow depth it is difficult to carry out remedial jobs. Conventional gas lifting is not possible in such cases. Lift modes like SRP or ESP are not possible as they require leak proof casing as formation gas is released through tubing casing annulus. In such cases generally a well would have to be abandoned.
In conventional gas lift (Fig - 1), gas is injected through the casing x tubing annulus and production is taken from the tubing. Generally,

frictional losses from downward flowing gas in the casing tubing annulus in most of the installations is very small due to higher annulus area and can be neglected without noticeable error. Hence, design is done considering increase in gas injection pressure with depth due to weight of the gas column.
3. DETAILED DESCRIPTION OF THE INVENTION:
The present innovation takes into consideration gas injection through the macaroni string and annular well fluid flow through the ann'ular space between 2 7/8 " tubing and 1 3/8" macaroni strings. As the flowing conduit size is small, frictional losses are to be accounted for.
As per the design carried out using a suitable multiphase flow correlation, the well would produce 25 bbl /day operating from 800m depth with approximately 500 m3/day of injection gas. At low injection gas quantities frictional losses are not significant and the injection gas pressure increases with depth due to weight of the gas column. The frictional losses depend upon the injection pressure and injection quantity. When the injection gas quantity is increased beyond a limit, the frictional losses will become more prominent thus leading to decrease in injection gas pressure with depth.
Modifications made in the existing conventional completion.
• A 1 3/8" Macaroni tubing string with provision of in-house designed fabrication (Fig - 2) to house 1" conventional gaslift valves inside is run inside the 2 7/8" tubing string for unloading and operating purpose.
• Gas is injected through this macaroni tubing and production is taken through the annular space between 2 7/8 " tubing and 1 3/8" macaroni strings.{ Figure-3)

• The leaking 5 ½ production casing is isolated by a packer run on 2 7/8" tubings.{ Figure-3)
The macaroni string is hooked up at the surface to the crown valve bull-plug flange of the X-mas tree with in-house developed and fabricated flange connection .(Figure-3).
4. FIELD APPLICABILITY:
Two wells with similar problem of damaged casing at shallow depth were earlier completed with open end macaroni tubings inside the 2 7/8" production tubing without any GLVs and with necessary modifications in the surface hook-up as discussed above. The open end macaroni tubing shoe is kept at the desired depth depending on tubing and available injection pressures. The wells were initially unloaded with high pressure air compressor application, due to insufficient available injection pressure, followed by gas injection to keep it under continuous flow .This open end completion has the limitations that interruptions in the injection gas supply or decrease in injection gas pressure, would make the well to cease after some time as the casing pressure would not be sufficient to lift the tubing load .In actual field operation with this type of completion, problems were encountered as the wells ceased due to fluctuations in injection pressure. Such wells required frequent air compressor application to unload the wells to keep them on production. Moreover, increase in the tubing pressure over a period due to possible increase in water cut may need the macaroni tubing to be set at new desired depth as the existing injection pressure would not be sufficient enough to continuously operate the well from the previously set depth. In one

well the setting depth of the macaroni string had to be changed due to tubing pressure variations under actual field conditions.
To alleviate such problems, the present completion with GLVs on macaroni tubings inside 2 7/8" tubing string is attempted. This completion has the advantages over simple open end completion that it is completed with upper unloading valves. This will take care of both fluctuations in the injection pressure and tubing pressure changes as the upper GLVs help in unloading the well to the desired depth as in the case of conventional gas lift system.
5. SUMMARY OF THE INVENTION:
The completion with GLVs on macaroni tubings inside 2 7/8" tubing string has the advantages over simple open end completion that the new completion is done with upper unloading valves. This will take care of both fluctuations in the injection pressure and tubing pressure changes as the upper GLVs help in unloading the well to the desired depth as in the case of conventional gas lift system. Wells with damaged casing at shallow depths, which otherwise would have to be abandoned and slim hole wells can be put on gas lift effectively.

BRIEF DESCRIPTION OF DRAWINGS
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
1) Fig-1 is a diagram showing conventional gas lift completion.
2) Fig -2 is a diagram showing housing for 1" Gas Lift Valve.
3) Fig 3 is a diagram showing the invented Gas lift completion with modified surface Hook-up.

We claim:
1. Production life of wells with damaged casings at shallow depths, which otherwise would have to be abandoned, can be prolonged with new innovative gas lift completion with macaroni tubing carried gas lift valves.
2. The completion includes (refer Fig 2 & 3 )

• Isolation of the damaged / leaking production casing with a packer run on normal production tubing (2 7/8" or above)
• A 1 3/8" Macaroni tubing string with in-house designed fabrication to house 1" conventional injection pressure operated gaslift valves inside is run inside the production tubing string ( 2 7/8" or above ) for unloading and operating purpose.
• Hooking up of the macaroni string at the surface to the crown valve bull-plug flange of X-mas tree with in-house developed and fabricated flange connection.
• Injection of gas through macaroni tubing and production through the annular space between tubing (2 7/8" or above) and 1 3/8" macaroni tubing.
3. The upper Gas lift valves help in unloading the well to the desired
depth and controls fluctuations in injection pressure and tubing
pressure.