1. 1 Formation Evaluation Exercise For Subsurface Methods Geology Course 4233 By Richard Andrews March 5, 2009

2. 2 GR & SP RESISTIVITY 2 Rxo/Rt - 0.5 1 10 100 1K Calculate S w in this zone every 2 ft. Cromwell Sandstone SP GR shallow deep Rxo/Rt

3. 3 GR & Cal Density & Neutron Φ 6 in 16 30 20 10 0 Cromwell Sandstone Calculate S w in this zone every 2 ft. Note: This log is shifted down 2 ft from resistivity log.

4. 4 GR & CAL Density & Neutron Porosity 0 API 150 30 20 10 0 6 in. 16 3700 3800 Red Fork Sandstone (3670-3690) Bartlesville Sandstone (3758-3792)

5. 5 GR & SP RESISTIVITY 0 API 150 1 10 100 1k 3700 3800 Red Fork Sandstone (3670-3690) Bartlesville Sandstone (3758-3792)

6. 6 GR & SP RESISTIVITY 0 API 150 1 10 100 1k Mississippian Limestone zone Calculate S w every 2 ft in this zone (6190’-6260’). GR & CAL Density & Neutron Porosity 0 API 150 30 20 10 0 6 in. 16

7. 7 Questions for formation evaluation exercise 1.Identify zones having hydrocarbon potential throughout the designated intervals in all wells. Calculate S w every 2 feet in the indicated zones using Excel spreadsheet. 2.Identify the expected type of hydrocarbon in each of the 4 zones. 3.In the Red Fork & Bartlesville sandstones: a.How clean are they?? b.What is the GR log profile telling you about the depositional setting and areal distribution of these two sandstones deposits? c.Explain the behavior of the density and neutron porosity logs across these two intervals. 4.In the Cromwell sandstone: a.Why is the density-neutron separation different in the top of the interval versus the bottom? b.Identify zones having permeability. c.Why is there no separation between the shallow and deep resistivity recordings from 6172-6206? d.Explain the behavior of the Rxo/Rt log in detail. e.If this well was drilled using 9-pound mud and the virgin reservoir pressure was 2500 psi, was this well drilled over or under-balanced?. Would you expect invasion in a permeable formations?