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Hi all,
I have carried out PBU in a gas well (exploratory well), after for about 15 hrs of production. The diagnostic plot was shown in the figure..
Here, I am not able understand the reason for this type of behavior. THP before build up was almost zero, but the well was producing little amount of gas. well was completed bare foot with 150 m column open, and no activation was carried out using nitrogen or compressor application. After mud replacement with water, well came on self after producing water for approximately 12-15 hrs with intermittent gas flow.

can any one suggest me what will be the reasons for this kind of behavior. Why the derivative curve crosses the delta P curve...?