By:Dr. Bernt Aadnoy, University of Stavanger/BECH Wellbore Flowcontrol AS
Date:29th of March 2012

The initial objective of the fixed type ICD’s, which now can be seen as mature technology, was to delay water coning and water cut in long horizontal wells.  The autonomous (self-regulating constant flow/injection) AFD improve this further.  In the following, another aspect of the two inflow control valves is addressed:  The effects on the recovery rates.

Figure 1:  Performance curves for standard fixed choke type ICD (green) and for BECH AFD (blue)

The figure shows the performance curves of a standard ICD compared to the performance of the BECH AFD.  As observed, the ICD shows a decrease in flow with dropping pressure, whereas the AFD shows a nearly constant flow.  An example will demonstrate the consequences of these performance characteristics.

Two cases are compared, one with each of the valves.  Example input data are:

Horizontal well, 300 inflow control valves, length of reservoir contact is 3600 m

Initial flow rate is 9900 bpd

Recoverable oil volume estimated to 108 barrels

Performing drainage analysis using the performance characteristics above, the time it takes to drain the reservoir was estimated.  The results are given in the table below.  Because the BECH AFD maintains nearly constant flow until the reservoir is drained it drain s much faster than the ICD with declining production rates.

The autonomous valve can play an important role in the field economy as it can drain the field at nearly half the time of the ICD, with an improved performance.  The main drivers for implementation of the new BECH AFD can be summarized as follows:

•Higher production rates

•Minimize/delay water cut

1. •Perfect for controlled flow in injection wells
   

To the BECH web site