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:

PTA Type	Well flow status
Drawdown Test (DD)	FLOWING
Injection Test (INS)	FLOWING
Build-up Test (BUS)	SHUT-IN
Fall off Test (FOS)	SHUT-IN
Multirate Step Test (MRST)	FLOWING
Pressure Interference Test (PIT)	FLOWING / SHUT-IN

Objectives

Primary deliverables	Math Symbol	Conditional Deliverables	Math Symbol
Assess current formation pressure	$\begin{array}{l}p_e\end{array}$	Assess initial formation pressure assuming no or little historical interference with offset wells	$\begin{array}{l}p_i\end{array}$
Assess skin-factor	$\begin{array}{l}S\end{array}$	Assess formation damage Assess formation penetration Identify fracture-network development around the well
Assess formation transmissibility	$\begin{array}{l}\sigma\end{array}$	Assess permeability assuming flowing thickness $\begin{array}{l}h\end{array}$ is known Assess flowing thickness assuming permeability $\begin{array}{l}k\end{array}$ is known Assess water-oil column assuming permeability $\begin{array}{l}k\end{array}$ and flowing thickness $\begin{array}{l}h\end{array}$ are both known	$\begin{array}{l}k\end{array}$ $\begin{array}{l}h\end{array}$ $\begin{array}{l}h_{OWC}\end{array}$
Assess minimum drainable volume around the well	$\begin{array}{l}V_\phi\end{array}$	Assess minimum hydrocarbon reserves around the well Assess drainage area around the well assuming flowing thickness $\begin{array}{l}h\end{array}$ is known Assess flowing thickness assuming the drainage area $\begin{array}{l}A\end{array}$ around the well is known Assess boundary proximity assuming the circular boundary	$\begin{array}{l}V_{hc}\end{array}$ $\begin{array}{l}A_e\end{array}$ $\begin{array}{l}h\end{array}$ $\begin{array}{l}r_e\end{array}$
Assess minimum drainable area around the well	$\begin{array}{l}A_e\end{array}$
Identify boundary type	$\begin{array}{l}PSS, \, SS, \, BAFFLE\end{array}$
Identify fracture presence and assess its size	$\begin{array}{l}X_f\end{array}$
Assess the fracture opening threshold	$\begin{array}{l}\delta P_{X_f}\end{array}$
Assess the presence $\begin{array}{l}r_{ext}\end{array}$ of remote reservoir composition areas and its transmissibility $\begin{array}{l}\sigma_{ext}\end{array}$		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

PTA Type Library

PTA Sensitivity Analysis

Type-Curve Matching

Samples


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

Page tree

Objectives

Interpretation

Samples

See Also

References

Page tree

Pressure Transient Analysis (PTA)

Objectives

Interpretation

Samples

See Also

References