1. Petroleum Engineering 406 Lesson 4 Well Control

2. Read Well Control Manual –Chapter 9 Homework 2 Due Feb. 3, 1999

3. Content Development of Abnormal Pressure Properties of Normally Pressured Formations Properties of Abnormally Pressured Formations Casing Seat Selection

4. Knowledge of Pore and Fracture Pressures Leads to: More effective well planning Maximize penetration rates with balanced drilling Safer and more economical selection of casing points Minimize trouble due to lost circulation and kicks

5. Knowledge of Pore and Fracture Pressures Leads to: Better engineered production and test equipment Better understanding of local geology and drilling hazards More accurate analysis of drilling data and electric logs

6. Normally Pressured Formation Fluids Squeezed out with compaction

7. Abnormal Formation Pressures Due to: –Incomplete compaction –Diagenesis –Differential Density in Dipping Formations –Fluid Migration –Tectonic Movement –Aquifers –Thermal Effects

8. Incomplete compaction Fluids trapped in place Fluids begin to support overburden

9. Diagenesis At 200 o F to 300 o F Clays undergo chemical alteration. Montmorillonite clays dehydrate and release some of the bound water into the space already occupied by free water, increasing pressure

10. Differential Density in Dipping Formations

11. Fluid Migration

12. Tectonic Movement - Uplifting

13. Tectonic Movement - Faulting

14. Aquifers

15. Thermal Effects Theories –Increased temperature with depth and chemical reactions cause increased pressures –Increased pressures caused increased temperatures

16. Salt Formations DepthDepth Pressure Gradient Pore press. gradient Overburden gradient Salt formation

17. Shale Properties used to Predict Pore Pressures Shales are used because: –Most pressure transition zones occur in relatively thick shales –Properties of clean shales are fairly homogeneous at any depth, and can be predicted with some degree of accuracy.

18. Shale Properties used to Predict Pore Pressures Shales are used because: –A deviation from the expected can be interpreted as a change in pressure gradient –Detecting these deviations in low permeability shales gives an early warning prior to drilling into pressured permeable formations, thus avoiding kicks.

19. Normally Pressured Shales Porosity - Decreases with depth Density - Increases with depth Conductivity - Decreases with depth Resistivity - Increases with depth Sonic travel time - Decreases with depth Temp. gradient - Relatively constant

20. Abnormally Pressured Shales Porosity - Higher than expected Density - Lower than expected Conductivity - Higher than expected Resistivity - Lower than expected Sonic travel time - Higher than expected Temp gradient - Increases

21. Porosity DensityConductivitySonic Shale Density

22. Temperature gradient - Increases DepthDepth Temperature Normal Trend Top of Geo-pressure

23. Pore Pressure Prediction Occurs: Prior to drilling During drilling After drilling

24. Before Drilling Offset mud records, drilling reports, bit records, well tests Geological Correlation

25. Before Drilling Open Hole Logs from offset wells

26. Before Drilling Seismic data

27. During Drilling Kick - SIDPP and HSP in DP can give accurate measurement of formation pore pressure LOT - gives accurate measurement of fracture pressure

28. During Drilling Correlation of penetration rate to offset logs Changes in shale penetration rate

29. During Drilling Shale density Change –Mercury pump –Mud balance Fill mud balance with clean shale until it balances at 8.33 ppg Fill the balance cup with water and determine total weight Calculate shale bulk density: –SBD=8.33/(16.66-Total Weight)

30. During Drilling Shale density Change - Density column

31. During Drilling Mud gas content change

32. During drilling Shale cutting change

33. During Drilling Mud chloride change Increase in fill on bottom Increase in drag or torque Contaminated mud Temperature change

34. During Drilling Abnormal trip fill-up behavior Periodic logging runs Drill-stem tests MWD or LWD tools Paleontology

35. During Drilling d c -exponent –P=K*(W/D) d *N e P=penetration rate of shale K=formation drillability W=weight on bit D=bit diameter N=rotary speed d=bit weight exponent e=rotary speed exponent

36. During Drilling d-exponent and d c -exponent

37. During Drilling

38. After Drilling Log evaluation Flow tests BHP surveys Shut-in pressure tests Analysis of mud reports, drilling reports, and bit records