Detecting a flood front in a cross bed environment

1. A method comprising:

making a measurement of a formation containing a flood front with a downhole electromagnetic sensor;

determining one or more cross-bedding model parameters of a cross-bedding model of the formation by fitting the measurement to the cross-bedding model;

determining a reservoir model using the one or more cross-bedding model parameters;

calculating a rock petrophysical parameter using the reservoir model and the cross-bedding model;

updating one or more cross-bedding model parameters of the cross-bedding model using the rock petrophysical parameter;

calculating a distance to flood front (DTFF) using the updated cross-bedding model; and

using the DTFF to make an operational decision.

2. The method of claim 1 wherein making a measurement with a downhole electromagnetic sensor comprises:

exciting a formation adjacent to the downhole electromagnetic sensor with an electromagnetic signal from a downhole electromagnetic transmitter to produce a signal scattered from the formation; and

measuring the signal scattered from the formation to produce the measurement.

3. The method of claim 1 wherein calculating the one or more cross-bedding model parameters of the cross-bedding model by fitting the measurement to the cross-bedding model comprises:

adjusting the cross-bedding model to minimize a misfit between the measurement and a predicted measurement calculated by the cross-bedding model; and

calculating the one or more cross-bedding model parameters of the cross-bedding model from the adjusted cross-bedding model.

4. The method of claim 1 wherein calculating the rock petrophysical parameter comprises:

using a petrophysical relationship to calculate a water/oil saturation from the cross-bedding model; and

calculating the rock petrophysical parameter using the reservoir model and the water/oil saturation.

5. The method of claim 1 wherein updating the cross-bedding model using the rock petrophysical parameter comprises:

calculating water/oil saturation using the rock petrophysical parameter; and

updating the cross-bedding model from a petrophysical relationship and the water/oil saturation.

6. The method of claim 1 wherein the operational decision is selected from a group of operational decisions consisting of closing a valve in a production string, closing a valve in a production string to maximize hydrocarbons and minimize production agents, and opening a valve in a production string to maximize hydrocarbons and minimize production agents.

7. The method of claim 1 further comprising:

using the reservoir model to calculate future values of oil/water saturation; and

wherein the operational decision is made using the future values of oil/water saturation.

8. The method of claim 1 , wherein the one or more cross-bedding model parameters include at least one parameter selected from a group consisting of vertical resistivity (Rv), horizontal resistivity (Rh), the DTFF, cross-bedding elevation (θ), and cross-bedding azimuth (ϕ).

9. The method of claim 1 , further comprising:

determining a misfit between the measurement and a predicted measurement calculated by the cross-bedding model; and

iteratively performing said determining the cross-bedding model, determining the reservoir model, calculating the rock petrophysical parameter, and updating the one or more cross-bedding model parameters until the misfit is below a threshold.

10. A non-transitory computer-readable medium on which is recorded a computer program, the computer program comprising executable instructions, that, when executed, perform a method comprising:

making a measurement of a formation containing a flood front with a downhole electromagnetic sensor;

determining one or more cross-bedding model parameters of a cross-bedding model of the formation by fitting the measurement to the cross-bedding model;

determining a reservoir model using the one or more cross-bedding model parameters;

calculating a rock petrophysical parameter using the reservoir model and the cross-bedding model;

updating one or more cross-bedding model parameters the cross-bedding model using the rock petrophysical parameter;

calculating a distance to flood front (DTFF) using the updated cross-bedding model; and

using the DTFF to make an operational decision.

11. The non-transitory computer-readable medium of claim 10 wherein making a measurement with a downhole electromagnetic sensor comprises:

exciting a formation adjacent to the downhole electromagnetic sensor with an electromagnetic signal from a downhole electromagnetic transmitter to produce a signal scattered from the formation; and

measuring the signal scattered from the formation to produce the measurement.

12. The non-transitory computer-readable medium of claim 10 wherein calculating the one or more cross-bedding model parameters of the cross-bedding model by fitting the measurement to the cross-bedding model comprises:

adjusting the cross-bedding model to minimize a misfit between the measurement and a predicted measurement calculated by the cross-bedding model; and

calculating the one or more cross-bedding model parameters of the cross-bedding model from the adjusted cross-bedding model.

13. The non-transitory computer-readable medium of claim 10 wherein calculating the rock petrophysical parameter comprises:

using a petrophysical relationship to calculate a water/oil saturation from the cross-bedding model; and

calculating the rock petrophysical parameter using the reservoir model and the water/oil saturation.

14. The non-transitory computer-readable medium of claim 10 wherein updating the cross-bedding model using the rock petrophysical parameter comprises:

calculating a water/oil saturation using the rock petrophysical parameter; and

updating the cross-bedding model from a petrophysical relationship and the water/oil saturation.

15. The non-transitory computer-readable medium of claim 10 wherein the operational decision is selected from a group of operational decisions consisting of closing a valve in a production string, closing a valve in a production string to maximize hydrocarbons and minimize production agents, and opening a valve in a production string to maximize hydrocarbons and minimize production agents.

16. The non-transitory computer-readable medium of claim 10 , wherein the method further comprises:

using the reservoir model to calculate future values of oil/water saturation; and

wherein the operational decision is made using the future values of oil/water saturation.

17. A method comprising:

making a measurement of a formation containing a flood front with a downhole electromagnetic sensor in a producing well, the producing well having a plurality of sections of ports for receiving fluids, each of the sections of ports being openable and closable independent of the other sections of ports, one of the plurality of sections being located so that its ports align with the formation;

determining one or more cross-bedding model parameters of a cross-bedding model of the formation by fitting the measurement to the cross-bedding model;

determining a reservoir model using the one or more cross-bedding model parameters;

calculating a rock petrophysical parameter using the reservoir model and the cross-bedding model;

updating one or more cross-bedding model parameters of the cross-bedding model using the rock petrophysical parameter;

calculating a distance to flood front (DTFF) using the updated cross-bedding model; and

using the DTFF to make an operational decision, the operational decision including opening or closing the ports in the one of the plurality of sections being located so that its ports align with the flood front.

18. The method of claim 17 wherein making a measurement with a downhole electromagnetic sensor comprises:

exciting a formation adjacent to the downhole electromagnetic sensor with an electromagnetic signal from a downhole electromagnetic transmitter to produce a signal scattered from the formation; and

measuring the signal scattered from the formation to produce the measurement.

19. The method of claim 17 wherein calculating the one or more cross-bedding model parameters of the cross-bedding model by fitting the measurement to the cross-bedding model comprises:

adjusting the cross-bedding model to minimize a misfit between the measurement and a predicted measurement calculated by the cross-bedding model; and

calculating the one or more cross-bedding model parameters of the cross-bedding model from the adjusted cross-bedding model.

20. The method of claim 17 wherein calculating the rock petrophysical parameter comprises:

using a petrophysical relationship to calculate a water/oil saturation from cross-bedding model; and

calculating rock petrophysical parameter using the reservoir model and the water/oil saturation.

21. The method of claim 17 wherein updating the cross-bedding model using the rock petrophysical parameter comprises:

calculating a water/oil saturation using the rock petrophysical parameter; and

updating the cross-bedding model based on petrophysical relationships and the water/oil saturation.

22. The method of claim 17 wherein the operational decision is selected from a group of operational decisions consisting of closing a valve in a production string, closing a valve in a production string to maximize hydrocarbons and minimize production agents, and opening a valve in a production string to maximize hydrocarbons and minimize production agents.