Tubing connection basics

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Tubings are screwed together through connections, which could either be:

  • By means of integral joint (the most common type of connection on small diameter pipe),
  • Or by using a coupling (the most common connection); a collar with internal threads used to join two sections of threaded pipe.

Selection of tubing connections:

The type of tubing connections selected for a completion will depend mainly on the well characteristics. The connection must be able to contain the produced fluids safely and at the maximum pressures anticipated.

The basic requirements of a tubing string connection are:

  • Strength compatible with the operational requirements of the string during, and after running;
  • Sealing properties suitable for the fluid and pressures expected;
  • Ease of stabbing during make-up, and safe breakout when pulling the tubing;
  • Resistance to damage, corrosion, and erosion.

Types of thread connection:

There are two types of thread connection: API and Premium.

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Subsurface Safety Valve Basics

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Safety valves are designed to automatically shut in the flow of a well in the event surface controls fail or surface equipment becomes damaged. They are classified according to the location from which they are controlled – surface or subsurface. In this article, subsurface safety valve types, operating systems, working principle, setting depth, and selection process are presented.

It is advisable, and in most cases mandatory, to have a secondary means of closure for all wells capable of natural flow to the surface. The installation on of a sub-surface safety valve (SSSV) will provide this emergency closure capability.

Courtesy Halliburton

Types:

To isolate the tubing, there are two basic types of safety valves:

  • Tubing conveyed: Tubing Retrievable Subsurface Safety Valve (TRSV),
  • Wireline conveyed: Wireline Retrievable Subsurface Safety Valve (WRSV)

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Advantages & Disadvantages of Jet Pumps in Oil Well Applications

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This article will present the typical ranges of jet pump operating parameters and discusses the advantages and disadvantages of jet pumps in oil wells applications.

Jet Pump Operating Envelope:

Advantages and disadvantages of jet pumps:

  • Advantages:

Jet pumps have several advantages such as:

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How Does Jet Pump Work?

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The jet pump operates by pumping power fluid at high pressure and rate from surface to activate/drive a downhole pump. Looking at the downhole jet pump, there are three main components:

  • Nozzle,
  • Throat,
  • And Diffuser.

The nozzle and throat are the key components of a jet pump. The ratio of the areas of these two parts is known as the area ratio of the pump and it determines the performance characteristics of the pump. Pumps with the same area ratio have the same performance and efficiency curves

Jet Pumps operates on Venturi principle. Above the JP, before entering the nozzle, the power fluid has high pressure (designated as PN) and low flow velocity.

While the power fluid passes the nozzle, due to the decrease in flow area it is transformed from low velocity, high static pressure flow to a high velocity, low static pressure flow (PS). This creates a pressure drop below the nozzle which drives the reservoir fluids into the pump.

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Jet Pumps Working Principle

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The first consumer of water jets pump was James Thompson back in 1852. In 1870, J. M. Rankin introduced the theory of jet pump operation, afterward, a number of papers have been published to develop the technology. The work of Gasoline and O’Brien in 1933 is considered to be the standard reference work. It has been based on both theoretical and experimental results. Since that time, developments in the technology have continued to the point that today jet pumps have high operational flexibility.

What is Hydraulic Lift?

As a general description, Hydraulic Lift (Jet Pumps) represents pumping power fluid at high pressure and rate from surface to activate/drive a downhole pump. Power Fluid can be water or oil.

With Jet Pump applications the completion needs to have minimum 3 flowing conduits:

  1. A conduit for power fluid injection (inside of the tubing in case of standard flow, and in the annular space in case of reverse flow).
  2. For reservoir fluid flow (below the JP & packer).
  3. And a conduit for commingled fluid flow to the surface.

 

Jet Pump working principle:

The jet pump artificial lift system is composed of two principal parts: the surface pumping equipment and the downhole jet pump. In the surface, the reciprocating pump transfers energy to the fluid increases its pressure, drove through surface piping, production tubing (or annular space) until the jet pump, placed on the bottom.

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