Zion Oil & Gas Inc (ZNOG)

[KyOil]

Well Test #3- Production Flow Test

We've talked about flow testing in previous posts too, but again, the source document gives a good definition:

Production flow test is long dynamic bottomhole pressure and production test for definition of
production deliverability of the wells by finding optimal correspondence of well head and formation
pressures and equipment.

Basically the idea is to see how much she will flow! My personal favorite as a redneck is the AOF test where the valve at the surface is wide open! It's fun to run anything wide open, but the well is seldom operated wide open as it is sub-optimal for long-term production. Basically, too much gas comes out versus oil produced when wide open. So, you want to throttle the well at an optimum point. To determine what point this is, the IP/IPR test is ran and is defined in the source document as:

Inflow performance (IP/IPR) is the graph describes the relationship between surface production
rate and BHFP (bottom hole flowing pressure) either the original pressure or the current average
value. The IPR curve is used to evaluate well current deliverability potential under a variety of surface
conditions, such as production against a fixed backpressure. In addition, the IPR can be used to
forecast future production at any stage in the reservoir’s life.

We've posted before about the VFP test which means Vertical Flow Profile. The VFP is important to know because it shows what pressure the wellbore fluid is at any depth in the well as fluids are flowing to the surface. The pressure profile in the production pipe is not simply the hydrostatic pressure at any depth because gas is a component of the formation fluid. Some gas may come into the pipe initially if its a mixed accumulation (oil and gas) in the reservoir. But even in a pure oil reservoir, gas is embedded in the oil and the gas is released as the fluid moves up the pipe towards the surface. This is two-phase flow and gets very complex. The embedded gas is a very beneficial property as the pressure it creates drives the oil to the well, and then lowers the backpressure on the formation from the production pipe as the fluid moves up the pipe. So, in MJ#1 case, it will easily free-flow oil when the formation pressure is 7,500 psi at a depth of 16,600 feet.



The complete chart is not captured in one screen shot, so the section on the next page showing "RT", or required test, for fluid collection is not shown in the image. For clarity, fluid collection is required and important properties like viscosity which determines flow resistance and API weight are measured. Fluid collection takes place first with wireline testing and again with production flow testing.