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Specific implementation of  Well Testing interpretation workflow of pressure transitions in terms of well properties and formation properties of connected subsurface reservoirs

Despite the explicit name It does not necessarily refer to analysis of a stand-alone pressure transient and also cover the complex pressure histories with numerous pressure transitions.

Both downhole and surface pressure records can be a source of information recoverable through PTA

The quantitative interpretation of pressure transitions is based on pressure diffusion model.


Below are the major types of PTA:


Objectives


Primary deliverablesMath SymbolConditional DeliverablesMath Symbol

Current formation pressure

p_e

Assess initial formation pressure assuming no or little historical interference with offset wells

p_i

Skin-factor

S

Assess formation damage

Assess formation penetration

Identify fracture-network development around the well


Formation transmissibility

\sigma

Assess permeability assuming flowing thickness h is known

Assess flowing thickness assuming permeability k is known

Assess water-oil column assuming permeability k and flowing thickness h are both known

k

h

h_{OWC}

Minimum drainable volume around the well

V_\phi

Assess minimum hydrocarbon reserves around the well

Assess drainage area around the well assuming flowing thickness h is known

Assess flowing thickness assuming the drainage area A around the well is known

Assess boundary proximity assuming the circular boundary

V_{hc}

A_e

h

r_e

Minimum drainable area around the well

A_e



Boundary type


PSS, \, SS, \, BAFFLE



Fracture presence and its size

X_f



Dynamic fracture opening threshold

\delta P_{X_f}



Proximity r_{ext} and transmissibility \sigma_{ext}of remote reservoir composition


Pick up the channel size/proximity

Pick up the oil-water front and its proximity

Pick up the oil-gas front and its proximity



Interpretation



Samples


Fig. 1. Transient responses in vertical producerFig. 2. Transient responses in horizontal producer




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