Drainage Radius Estimation

[elevenfourth]

Hello all !

I am doing a task of preliminary study of a field. So the wells are not drilled yet. I have the data of the grids, such as permeability, saturation, pressure, porosity. But I am not allowed to do reservoir simulations to estimate the drainage radius. All wells are vertical wells.
Do you know how to estimate the drainage radius of a well without assuming the well spacing, and by the given data only?

Thank you for your help !

[kochichiro]

Well, if you only have had well test data it would be easy to calculate - here is the lead -

[link Point to another website Only the registered members can access]
You can also provide me with your data and I'll calculate it for you depending on different skin scenarios. But remember it would be quick-look estimation and you must prove it by testing of newly drilled wells.

[ivan_aljeburi]

you can use the next equation:

Rin2=(K*t/phie * mio*Ct)
K is the permeability around the well
t is working time or drawdown time
phie is porosity
mio viscosity
Ct is total compressibility which equals formation compre.. plus fluid comress. here you need saturations to calculate fluid compress.

[vinomarky]

The two previous posts touch on the nub of the problem in that the drainage radius is a function of time until a barrier is reached. If your geology indicates good perm and homogeneous reservoir, then it will essentially be governed by your assumed interwell spacing for your given scenario. If your geology is not so good, then you'll have to make some assumptions based upon intra-connectivity of your reservoir. Well tests are unlikely (we hope) to give you any guidance, as generally if you detect barriers in the period that tests are conducted then the economics become very challenged. Well tests for commercial fields typically only tell you that the drainage radius will be at least a certain value (there are of course, always exceptions). In short, you mostly cannot separate well spacing assumptions from your drainage radius estimates - the radius may well be less than well spacing in the case of poor reservoirs and wide spacing - but you need to start with a notional development scenario to work it through.

[06pg22]

Formula for volumetric estimation can also be utilised to estimate Drainage Area (radius = SQRT (Area/pi))
In such case, use Cumulative Production rather HCIIP in the equation.
Formula assumes constant fluids saturation through out the production period.