Water Injectivity Decline

Well Test Analysis, Pressure and Production Monitoring........ etc.

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Bilal Amjad
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Location: اسلامی جمہوریہ پاکستان

Water Injectivity Decline

Post by Bilal Amjad »

Hi All,

I am working on water injectivity decline project in a sandstone reservoir. Injection wells needed to be subjected to periodic acid jobs. Produced Water Used was may or may not exposed to air. Water used was commingled water of nearby fields. Reservoir Permeability and porosity are as under

Reservoir Permeability:
Min = 1.1768
Max = 2950.7
Range = 2949.6
Mean = 116.28
Median = 35.177
Porosity:
Min = 0.05442
Max = 0.14983
Range = 0.09541
Mean = 0.09366
Median = 0.09304

To study the decline which things i need to focus or investigate? What experiments I must perform to identify the reasons behind the decline in the injectivity.
Pls suggest from your experiences and expertise
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FANARCO
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Post by FANARCO »

Dear Bilal,,,

The Injection rate is a factor of the difference in pressure between Bottom Hole Injection Pressure and the reservoir pressure and mobility ration K/u as well as wellbore and reservoir radii as per Darcy equation for radial flow.
Since all of the above are constant except dP. So, i think there is a skin damage occurred in this case and needs to be removed.
Acid Stimulation is one of these solutions.
malafat
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Post by malafat »

Bilal

One thing to note different from formation damage, in most of the Pakistani carbonates you can see geomechanical behaviour change by reservoir pressure. How is your average reservoir pressure changing? I mean if there is a decline on the average pressure, some fractures might close which will reduce the effective permeability as well as volume in connection.
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