Techshore Inspection Services-Kochi-official blog of Techshore Kerala: TECHSHORE INSPECTION SERVICES :Pressure involved in drilling

Techshore Inspection Services, Kochi Kerala- www.techshore.in explains the various types of Pressure involved in Drilling.

Types of Pressure Involved in Drilling-Techshore Kochi

Techshore Inspection Services, Kochi Kerala- Formation pressure

The pressure exerted by the fluid that get ‘s trapped inside the formation rock is known as formation pressure. Depending upon the formation pressure gradient, it is classified into two pressures:-

Normal formation pressure

Abnormal formation pressure - Techshore Inspection Services, Kochi Kerala

Normal formation pressure

Techshore Inspection Services, Kochi :- By the deposition of rock layer over one other, water from the formation is squeezed out of the pores due to overburden, this phenomenon is called as compaction. As the formation water escape through the formation rock, it formation pressure also changes down to a normal value. mostly accepted normal value is ranging from 0.433 psi/ft to 0.465 psi/ft. Thus the pressure within this range is known as normal formation pressure.

Abnormal formation pressure

The formation pressure which ranges from the normal value, ie 0.465 psi/ft is known as abnormal formation pressure. It is caused because of the reason that due to the overburden of formation water is formation rock tries to escape, loss by the impermeable formation that does not allow its normal escape, hence abnormal formation pressure is formed. The cause of abnormal pressure is due to.

Under compaction
Artesian effect
Faulting
Salt dome
Gas cap effect
Charged sands

Hydrostatic pressure- Techshore Inspection Services, Kochi Kerala

Techshore Inspection Services, Kochi Kerala-The pressure exerted on the formation to overcome the formation pressure by a static column of mud is known as hydrostatic pressure. Hydrostatic pressure is maintained by the density of mud. The hydrostatic pressure of the mud depends upon the true vertical depth of the well and mud density. Hydrostatic pressure is expressed in psi.

Hydrostatic pressure = tvd (in ft) * mud density (ppg) * 0.052

Where, 0.052 is the conversion constant

Pressure gradient

When the pressure of a fluid is calculated for a given unit length it is known as pressure gradient. The pressure gradient is the product of mud density (in ppg), conversion factor and unit length.

Pressure gradient = mud density (in ppg) * unit length (in ft) * 0.052

Swab and surge pressure

-Techshore Inspection Services, Kochi Kerala, When the drill string is lowered for drilling purpose or the at the time of tripping in, the string exerts a pressure on the mud column, this is known as surge pressure. Surge pressure is always taken as +ve.

When the drill string is raised during drilling purpose or at the time of tripping out, the string loses a pressure on the mud column, this is known as swab pressure. Swab pressure is always taken as –ve because there is a loss of pressure.

Bottomhole pressure (bhp) explained by Techshore Inspection Services, Kochi Kerala

"Bottomhole pressure is defined as the sum total of all the pressure that acts on the bottom of the hole. That is the pressure exerted at the bottom of the hole" as explained by Techshore Inspection Services, Kochi Kerala

Bhp = hydrostatic pressure + surface pressure +/- dynamic pressure

Dynamic pressure is the pressure exerted by the pipe movement, ie swab or surge pressure or either due to fluid movement, ie by annular pressure losses.

Techshore Inspection Services, Kochi Kerala also explains about Bhp during different Well operations:-

During drilling

Bhp = hydrostatic pressure + annular pressure losses

When not circulating

Bhp = hydrostatic pressure due to mud column

While tripping in

Bhp = hydrostatic pressure + surge pressure

While tripping out

Bhp = hydrostatic pressure – swab pressure

Maximum allowable annular surface pressure (MAASP) as per the works of Techshore Inspection Services, Kochi

According to Techshore Inspection Services, the Kochi, Kerala, Maximum allowable annular surface pressure is defined as the maximum pressure at the surface that a casing can hold with complete safety.

To get more ideas about the above please visit the youtube channel of Techshore Inspection Services, Kochi Kerala-www.techshore.in

Thursday, March 23, 2017

TECHSHORE INSPECTION SERVICES :Pressure involved in drilling