BALANCE OF MATERIALS USED IN OIL FIELDS OF CLASS 03 CLASS 04
The material balance applied to oil fields is a useful tool to determine with any certainty parameters such as the POES, GOES (N, m), determine the contribution of each mechanism of recovery ( Io, Ig, Iw) and the degree of uncertainty associated with the result, ie how far away the value of N calculated value of N real.
These results were obtained from the production history (Np, Gp, Wp, We) and the PVT data (βo, βg, βw, Rs) and the pressure-time for each request.
When using this type type methods to keep in mind that the reservoir model analyzed is a type tank, where it considers that the thermodynamic properties are uniform throughout the reservoir volume. For the reservoir simulation model used is different, is a partition of the field into smaller units and studying the properties of each part individually, thus achieving an outcome closer to reality.
a reservoir properties usually do not follow a linear behavior in time when pressure is changed, ie produced fluids it contains. One way to know how close is the result that obtained using the material balance equation and its particularization for the straight-line method is to make a least squares adjustment data and production history PVT. Finding the coefficients of the best line that fits the data we obtain the correlation coefficient between the data drive, and so know that both our results away from each other. A very close correlation or equal to 1 gives us an idea that our results are in line with expectations.
So how is it possible to know the rate of production of each drive mechanism proposed by Pearson, it is possible to determine the fractional contribution of all mechanisms affecting production.
graphically as is useful to understand the mechanisms contributing to production, to get an idea of \u200b\u200bwhat mechanism overwhelmingly favors the reservoir.
most important factors that represent the uncertainty of the results we get from errors in measurement and estimation of reservoir pressure, its PVT data, errors in the production history and the misinterpretation of pusher present.
At first we defined the relationship petroleum gas production, which is obtained by considering the relationship among all the gas produced and accumulated all the oil produced accumulated to a certain pressure. Similarly, we obtain the relation between the produced gas and oil produced for a specific moment. This relationship is known as gas - oil Instantly calculate and must resort to ecuanción Darcy and consider that the gas produced from both the free gas which is dissolved in oil.
Recalling some basic concepts of fluid saturation is the fraction of pore volume that it occupies. For a given pressure is possible to calculate the average hydrocarbon saturation in the reservoir.
So far we have been able to calculate the value of the POES (N), but this is not our only objective. A reservoir engineering should be able to make predictions about the behavior of oil and its variation over time. Schilthuis method allows us to predict how much oil can be produced to decrease to a certain pressure, assuming a value of N and PVT data.
To apply this model to predict certain considerations must be made.
The site should be volume (not associated aquifer).
discovery pressure equals the bubble pressure is say, a crowded field and there is no gas cap.
must be known water saturation
know the relationship between Kg and Ko, depending on the saturation of fluids.
Taking into account these considerations, the material balance equation we have in the following way.
Since our objective is to obtain the value of Np and know how realistic to be our prediction, then we will work with the following equation:
Steps to develop the method of Schilthuis
1. Specify how work pressure intervals.
2. assume a value of ΔNp / N between 1 and 0.
3. Calculate Np / N
4. pressure for interest, finding SL through:
5. determine Kg / Ko.
6. Find the value of Ri:
7. Calculate ΔGp / N
8. Calculate Gp / N:
9. Find Rp
10. With the data obtained previously, return to the relationship, place and find that both depart from the ideal value (1).
If finding the relationship, its value is between 0.99 and 1.01, the value of ΔNp / N assumed is correct and can be found from Np Np / N, otherwise, we must assume another value ΔNp / N and follow all the steps again.
