Describe the upper completion in detail from interface with lower completion to, and including, the tubing hanger.

After the well has been drilled it has to be completed and prepared for production. There are 2 major types of completion: Upper completion (Well control) and Lower completion (Production control).

Upper completion (Well control):

Production packer: Seal off the space between the production tubing and the casing. Packer is considered to be primary barrier for the well during well intervention and it located just above the producing zone. There are two types: Permanent (fixed with slips, used in production wells) and retrievable (runs as part of the tubing, easy to lock and unlock)

Packer fluid: packer fluids will limit corrosion of production tubing and production casing.

Production tubing: is a tube used in a wellbore through which production fluids are produced.

DHSW: downhole safety valve, which closes in case of emergency and it installed inside tubing approximately 50 m below the seafloor in offshore wells. DHSW acts as a failsafe to prevent the uncontrolled release of reservoir pressure in case of failure. There can be two 7” tubing-retrievable surface-controlled subsurface safety valves in case one valve can be used as a backup valve in a case of failure of the main one.

ASV: used in gas lift wells.

Expansion mechanism (PBR): polished bore receptacle (PBR)is installed in tubing to allow thermal expansion of the tubing.

Circulation valves / sliding sleeves: connections between the annulus and the tubing, injection of kill fluid into the well and control production from several zones.

Pressure and temperature gauge: pressure and temperature gauges are installed in each well for to obtain reliable data about downhole temperature and pressure in a reservoir. These systems are standard for the industry.

Tieback Seal Assembly: the tieback seal assembly is used to connect the lower to the upper completion and serves as an annular barrier. It makes easier to perform coiled tubing operations and run into the horizontal section with wireline.

Gas-lift valve: if the check valve fails, this can be replaced through the pocket on one side of gas-lift valve.

Lower completion (Production control):

Inflow Control Device: in order to increase the drainage area and it control the fluid-flow path from the reservoir into the flow conduit.

Screen Hanger: due the steep deviation of wells it recommends to set screen hanger. Some of the reservoirs need screens to control the sand production due the sandstones of the field are characterized by their high values of porosity and permeability.

Centralizers: during installation in the heel of the well, the centralizers decrease the screen packing and damage.

Gravelpack: reduce problems with sand production by placing special sand around screen or outside a perforated liner and inside the perforations.

Tubing hanger: is a component used in the completion of oil and gas production fields. Tubing hanger is installed at the top of the tubing head and run through the BOP. If we will decide to use horizontal X-mas tree than tubing hanger is will be placed above the wellhead. Crown plugs are part of the tubing hanger and they operate as the secondary barrier. Some hangers are developed for hydraulic control lines, SSSV´s, or other types of completion equipment and providing suspension of producing tubing. [7]

Figure 4: Design of Upper Completion.

Дата добавления: 2015-10-23