Gas Lift Production – Impact on Tubular

Connections

Presented by

Gloria A. Valigura, Shell International E&PPatrick E. McDonald, Mohr Engineering, a div. of

Stress Engineering

Presentation Objective

Discuss changes in well load conditions and the impact on tubular connections when applying gas-lift technology to wells that are no longer geo-pressured.

Discuss need to test (qualify) connections to meet or exceed life-cycle well loads

Original Well Design

• Well Design is driven by a multitude of load conditions.

• Casing Design is driven by the Well Loads

• Connection selection is driven by the Casing Design and Well Loads.

• Connection Design is driven by threading manufacturers to meet user required performance properties.

Connection Qualification

• The user needs to ensure level of testing is adequate for well usage.– Connection qualification ranges from

abbreviated threader in-house testing, to user-specific test protocols, as well as industry standard test protocol. Each is different.

– ISO 13679:2002 is the current petroleum industry standard for connection qualification. There are four Connection Application Levels (CAL).

Connection Design

The Manufacturer generally rates the Connection against the pipe body for the following Performance attributes – Axial loads (Tension, Compression)– Differential Pressure (internal, external)– Collapse (structural)– Dimensional (Maximum OD, ID Drift)

The connection is not required to be equal to the pipe and, most likely, is not rated equal to pipe for one or more of it’s performance property attributes.

Connection Design

The Manufacturer generally rates the Connection against the pipe body for the following Performance attributes – Axial loads (Tension, Compression)– Differential Pressure (internal, external)– Collapse (structural)– Dimensional (Maximum OD, ID Drift)

The connection is not required to be equal to the pipe and, most likely, is not rated equal to pipe for one or more of it’s performance property attributes.

Pipe Body Triaxial Stress Ellipse (VME)

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

10000

-1500 -1000 -500 0 500 1000 1500

Axial Load (Kips)

Pre

ssur

e (P

SI)

Tension

Compression

Internal Pressure

External Pressure

Connection Service Load Envelope

Changing Well EnvironmentGeopressured to Gas Lift

Incr easing Pr essur e

Depth

Tubing Pressure Gradient

under Geo-Pressured Flow

"A" Annulus Pressure

Gradient

Tubing Pressure Gradient

with Gas Lift

"A" Annulus Gas Pressure

Gradient

Dynamic Pressure Gradients Bring Challenges to Well Design and Connection Selection

Changing Well EnvironmentGeo-pressured to Gas Lift

Geo-pressured Well(Reservoir driven)

Gas Lift Well(Artificial Lift)

Tubing Environment•Oil production

•Internal Pressure gradient with axial load

•New connections and tubulars.

•Oil and Gas production

•Collapse Pressure gradient with axial load

•Used tubing and connections

Casing Environment•Internal Pressure Gradient – Atm. at surface

•Completion Fluid in “A” annulus

•Tension loading for most of string

•High Pressure Gas gradient from surface

•Higher compression loading from compaction

•Connections and casing old, worn, corroded

•Cement quality

Changing Well EnvironmentGeo-pressured to Gas Lift

Need to understand the change in loads on connections during life-cycle of the well – API connections, were typically qualified for

liquid (oil) service and for internal pressure with axial load.

– Gas service applications generally need the improved leak resistance of premium connections used in lieu of API connections. Activities to try to enhance API thread leak resistance performance include:

• API SR22 Work Group to enhance performance properties of API 8rd and BTC connections

• Exxon-Torque Position

Changing Well EnvironmentGeo-pressured to Gas Lift

Need to understand the change in loads on connections during life-cycle of the well– There are differences between the various

seal-ring grooved EUE 8rd connections on the market which may result in performance differences.

– Each premium connection product type will have a different service load envelope. And, within a product type, different service load envelope may exist.

Changing Well EnvironmentGeo-pressured to Gas Lift

The user is encouraged to ensure that:

• Testing level (connection application level) is adequate for well life-cycle usage.

• Connection service load envelope is greater than well life-cycle loads.– May need to adjust for load uncertainty.

Why Do Connections Need to be Qualified

• Connections are a high risk element of production tubing and casing

• Validates/invalidates threading manufacturer’s marketing claims

• Testing provides a reliable service envelope of operating pressures, loads, and temperatures for the size, weight, grade and thread tested.

• If well loads, pressures and temperatures exceed connection tested service load envelope, further qualification should be performed to expand tested service load envelope.

For Your Consideration

• In new wells– Qualify the connections to ensure that

service load envelope exceeds well life-cycle loads.

– In Use ISO 13679:2002 as the preferred connection test protocol.

• In existing wells– Evaluate potential degradation of the

casing and connections from time of installation.

For Your Consideration

• In existing wells (cont’d)– Casing – may wish to perform

qualitative risk assessment (QRA) to evaluate possibility of an event and the consequences of that event.

– Remediation could include running a liner

For Your Consideration

• In existing wells (cont’d)– Tubing – Replace when necessary to

meet well load requirements.– Tubing Connections – Use after

performance is validated resulting in an appropriate service load envelope. As a test protocol, use ISO 13679:2002, with modifications to meet gas-lift applications.

• JIP?

Thanks for your time.

Any Questions?