How could you estimate reservoir pressure without welltesting?

[ahorkado]

Hi, pals.. Would you mind helping me with this issue?. I'd want to know if there are formulates, methods or something to estimate reservoir pressure without welltesting, coz' I gotta analize old wells without buildup's

[DAH7542]

Dear ahorkado,

Consider the following:

1. Material Balance analysis
2. Slope Analysis of the Hall Plot (only If you have current water injectors) might work for you: refer to SPE paper 93879
3. Use fluid level measurements after field or well shut-in periods of enough duration to be representative of local reservoir pressure. You can estimate this time (i.e. the time required for a shut-in period to reach stabilized conditions) with the well-known formula for stabilization time (see equation 2.40a and 2.40b in the book by Earlougher "Advances in Well Test Analysis", page 18-19). This equation often assumes circular drainage areas with centered wells, but corrections are available in many books for different drainage area shapes.
4. Use Darcy equation to back calculate the reservoir pressure if you have a reasonable estimate of all other parameters involved: Pwf and flow rates are usually measured in the field, and you might also have an idea if the flow is in Pseudo Steady State or Steady State (don't use it under transient flow since Darcy eq. is not valid). However, uncertanty might be an issue in regard to the wellbore damage or skin, drainage radius, drainage area shape, effective permeability and even net true stratigraphic thickness. Note: Rate Transient Analysis such as Fetkovich and/or Blasingame type curves are very useful to establish the flow regime: transient or boundary dominated, use RTA if needed to make sure you are applying Darcy eq. during boundary dominated flow conditions.

[vinomarky]

Look through your producing history for a step change in rate/pressure (ie choke adjustment), then use the method I've outlined here;

[link Point to another website Only the registered members can access]