DST Interpretation Samples

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Basic Analysis


Deviation from standard flow/shut-in DST	Multiple test charts on different intervals	Wrap around effect on single interval test

Influence of clock speed	Various clock malfunctions	Hole entry difficulties

Plugging in shut-in tool	Stair stepping adjacently	Complete plugging in anchor

Solid plugging in valve parts	Plugging stimulates an additional shut-in period	Intermittent plugging and clearing

Advanced Analysis


Influence of gas/water proportions on flow curve shape	Increasing pressure (gas) due to co-production	Very high transmissibility of gas

Skin Effect


Typical skin damage	Decreasing pressure due to changing skin (gas)	High skin damage (gas)

Damage vs. improvement	Tight vs. permeable with vs. without damage

Deep Damage


Detection by contrasting shut-in curves

Depletion


Depleting oil or gas	Decreasing bottomhole due to reservoir depletion (gas)	Declining initial shut-in

S-Curve (Oil vs. Gas)


Very low kh	Undersaturated oil flow pressures < bubble point	Oil flow at surface rising pressure

Producing vs. solution gas/oil ratios