Communication Test
Communication testing is useful for determining if multiple wells are drawing from the same reservoir.

There are two types of communication testing. The first type is direct communication testing. This can be done by (1) taking two producing wells and shutting one in and monitoring the pressure response as the other continues to produce, or (2) by shutting in both wells and then turning one back on and monitoring the pressure response at shut in well, or (3) if a field is just being put on production, turn on one well and leave the other one shut in and monitor the pressure response. As the producing wells cone of influence expands, once it reaches the shut-in well a pressure response should be observed. The time this takes depends on the hydraulic diffusivity of the reservoir as well as the distance between the wells.

The other type of communication test is referred to as inferred communication testing. This can be done by either changing the rate in one well and seeing if the rate changes in the other well. Another approach is to shut in both wells and observe when boundaries are hit for both wells. If they occur at relatively the same time and the boundary contacts have complimentary shapes then this is a good indication that the wells are communicating. However, the problem with this test is that you have to have been producing both of the wells long enough so that the radii of investigation have intercepted each other. If they haven't, then it does not matter how long you shut in the wells--they will never reach that point because neither well has been able to see that far into the reservoir.

One common communication test is pulse testing. This consists of opening and closing the choke a few times to send pressure and rate pulses through the reservoir. Then, if the pressure changes are observed at the other well, the wells are in communication. Again, the only way this can work is if the radius of investigation of the pulsed well has already reached the shut in well before the pulsing process begins. Otherwise, it does not matter how many times you pulse it the response is never going to be seen by the other well.

NOTE: The textbook assumption for this test is that when the well first turns on it experiences the entire reservoir at once and all of the fluid begins to move at once (remember, the law of relativity applies everywhere except in classical reservoir mechanics). The problem with that is it's very far from the truth. One molecule cannot move until the molecule in front of it moves and this process is governed by hydraulic diffusivity. So this means that it is an ongoing process and a part of a reservoir cannot be seen until the radius of investigation has reached that far in the reservoir. A good comparison for this is at a stop light. When the light turns green all of the cars don't start moving at once. Instead, the first car starts to move then the car behind him moves and so on.

Multiple gauges are needed for this type of test so with the low cost, high resolution, and ease of installation of both the DATAPORT™ and DATATRAP™ or PR600™, this test is an ideal application for these gauges (if the tests can be performed from the surface, i.e. the fluid is single-phase in the well bore). If they cannot be tested from the surface, high-resolution downhole gauges should be used.

NEWS

Aug. 19th 2011 - Probe Holdings, Inc. has acquired the assets of AKS Technologies, Inc of Houston, USA, in an undisclosed cash and equity transaction.
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