What Does Wellhead Treating Pressure (WHTP) Mean?
The wellhead treating pressure (WHTP) is the surface pressure at the wellhead during pumping. WHTP can be calculated once the bottomhole treating pressure (BHTP) is known. Obtaining the BHTP is a vital part of design and planning for a fracking project.
Once the BHTP is known, further calculations must be done to obtain the pressure of fluid required at the surface of the well to achieve the BHTP. In addition, the maximum pressure requirements of the well itself are set based on the WHTP and BHTP.
Trenchlesspedia Explains Wellhead Treating Pressure (WHTP)
Once a fracking process starts, engineers keep close watch over the actual pressures and flow rates relative to the design. When the deviation becomes too large, the process is stopped to determine the reasons. Applying a higher WHTP and therefore BHTP than the design may eventually cause the well to fail.
It is also important to note that measuring bottom hole pressure (BHP) is difficult and expensive. A common approach is, therefore, to measure the wellhead pressure (WHP) and calculate BHP based on depth and losses.
The WHTP can be calculated once the BHTP is known using the formula:
WHTP = BHTP + Ppipe + Pperf + Phyd
where, Ppipe is the friction pressure resistant to flow down the wellbore during pumping operations
Pperf is the pressure drop across the perforations, and
Phyd is the hydrostatic pressure of the fluid in the wellbore which is fluid dependant