Frictional Pressure Loss Components in the Rig Circulating System

Frictional Pressure Loss: Frictional Pressure Loss is pressure loss created by fluid flowing through the flow path. It is a function of fluid property (density, viscosity, gel strength), velocity of fluid, characteristic of flow path (hole size/drill string size). Frictional pressure loss affects on pump pressure because higher frictional pressure loss, higher pump pressure is required to maintain the pump rate.

In order to clearly demonstrate the pressure loss component in the drilling rig system, the diagram below describes pressure loss each flow path of drilling fluid in the total rig circulation system.

The Diagram of Frictional Pressure Loss in Circulation System

Parameters, which affect pump pressure, are as follows:

1. Fluid properties especially mud weight, viscosity, gel strength and yield point affects directly on pump pressure. Higher mud weight, viscosity, gel strength and yield point, higher pump pressure requires to maintain pump rate.

2. Pump rate is another factor that affects directly on pump pressure. This is a basic concept when higher pump rate is needed; higher pump pressure is required.

3. Hole size/drill string size: Smaller internal diameter of both hole and drill string, higher velocity of fluid flow is created at same pump rate. Higher velocity creates more frictional pressure loss. High pump pressure is required in order to maintain pump rate because there is additional pressure loss due to smaller hole size and drill string.

4. BHA and Bit: Due to small inner area, BHA and bit can cause majority of pressure loss.  Hence, BHA design/selection and bit nozzle selection are critical for hydraulic design.

5. Well Depth: The deeper of the well is, the more pressure loss will occur . It means we need more pump capacity to achieve the drilling goal.  Depth of the well is based on geological targets underneath the earth by geologists. This part will influence on how to select the proper rig capacity in order to meet hydraulic proposes of the wells.

I hope this post will help you understand more about pressure loss in the drilling rig : )

Any comments are always welcome.

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4 Responses to Frictional Pressure Loss Components in the Rig Circulating System

  1. badih says:

    Dear sir:

    I have well with following parameters:
    1- TD = 10000 ft
    2- casing 7″, 29# set and cemented at 10000 ft
    3- tubing 3″1/2 9.2# run to 10000 ft, with two perforated couplings one 1.5mm at 3000 ft the second 2 mm at 4500 ft without production packer
    4- the tubing and annulus is filled by fresh water
    5- we need to pump air to evacuate the well from water
    which is give us less pressure on the formation, to pump the air in the annulus or in the tubing

  2. Joseph says:

    I really enjoyed this post. I hope learn more from you

  3. Shahid Solanki says:

    Dear Team Dr.For.Com
    I appreciate the Drilling Formulas .com team for excellent coverage on the petrolatum industries related techniques and its formulas. On other hand simplify presentation 4 easy understanding .

    Try to cover the OIL industries Standards also.

    Warm regards .
    S S SOLANKI, Chief Engineer (Production).

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