Welltest 106: Impulse & Closed Chamber Tests

Impulse Tests are Useful for many Other Applications. Surface casing-vent tests can be conducted using the closed-chamber method. Closed-chamber drill stem tests. Pre-frac’ evaluations and frac’ falloff tests. Alberta AER Initial Pressure requirements can be achieved with a variety of subsurface pressure PID techniques: Recorders on bottom before perforating (used with TCP guns)Recorders attached to the drop bar (use a spring to dampen impact on gauges)Recorders on bottom after perforating (may have wellbore storage issues)Recorders on...

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Welltest 106: Impulse & Closed Chamber Tests

Welltest 106: Impulse & Closed Chamber Tests

Proving Movable Reserves. In this example a high permeability sandstone overlaid a shale zone. Decline curve analysis indicated natural gas (#LNG) reserves greater than volumetrics could justify. It was hypothesized that the shale gas reserves migrated vertically, due to pressure differential, to be produced with the sandstone reserves. The shale was perforated first and exhibited a pressure increase, thus proving additional movable gas reserves. The second perforation response was from the high permeability (high #AOF) sandstone. The PID...

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Welltest 106: Impulse & Closed Chamber Tests

Welltest 106: Impulse & Closed Chamber Tests

Perforation Inflow Distribution Diagnostic (PIDD) Tests. The PID #welltest is analogous to production logging when two or more intervals are perforated. Based on changes to the Dp/Dt slope, gas (#LNG) inflow and AOF ratios can be estimated. Starting with the interval of least anticipated influx potential, multiple perforation runs are conducted. Subsequent to each perforation run, pressures are allowed to build up for a set period of time, being a function of permeability and rate of pressure increase. It may be necessary to blow down the...

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Welltest 106: Impulse & Closed Chamber Tests

Welltest 106: Impulse & Closed Chamber Tests

Perforation Inflow Distribution Diagnostic (PIDD) Tests. The PID #welltest is analogous to production logging when two or more intervals are perforated. Based on changes to the Dp/Dt slope, gas (#LNG) inflow and AOF ratios can be estimated. Starting with the interval of least anticipated influx potential, multiple perforation runs are conducted. Subsequent to each perforation run, pressures are allowed to build up for a set period of time, being a function of permeability and rate of pressure increase. It may be necessary to blow down the...

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Welltest 106: Impulse & Closed Chamber Tests

Welltest 106: Impulse & Closed Chamber Tests

Perforation Inflow Diagnostic (PID) Tests—Modern Analysis. Colleague Florin Hategan suggests that formation net pay (h) be replaced by effective perforated pay (hp) thus generating formation permeability (kf) such that formation flow capacity becomes (kh = kf — h) (unpublished). Subsurface PID #welltests have proven very economic and effective for compliance with Alberta #AER Initial Pressure Gas (#LNG) and, especially, Initial Pressure Oil, requirements. Slug (Impulse) Analysis – Radial...

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