1. Petroleum Engineering 406 Lesson 3 Well Control

2. Read Well Control Manual –Chapter 7-8 Homework 2 Due Jan. 30, 2001

3. Content Equivalent Mud Weights - EMW Casing Seat Tests Kick Tolerance Differences in Kick Types Reaction of Gas in the Wellbore

4. Equivalent Mud Weight EMW - the total pressure exerted at a given depth expressed in ppg equivalent EMW = Surf. Press./(0.052*TVD int )+MW –or EMW = Total Press. /(0.052*TVD int )

5. Equivalent Mud Weight Examples: –KWM –ECD - Equivalent Circulating Density ECD = Ann. Fric./(0.052*TVD)+OWM –Frac gradient –Pore pressure, etc

6. Casing Seat Tests We test casing seats to: –Determine max pressure that formation can withstand –Determine if we have a good cement job

7. Casing Seat Tests LOT - Leak-Off Test –Measure the fracture pressure at casing seat –or, Maximum pressure the formation can withstand prior to fracture Volume pumped PressurePressure Leak-Off Fracture Initiation Fracture Extension Casing Test

8. Casing Seat Tests PIT - Pressure Integrity Test (FIT) –Determine if the casing seat can withstand a pre-determined pressure Test Pressure = (EMW-MW)*0.052*TVD casing seat

9. Kick Tolerance Maximum Casing Pressure - MCP Maximum Allowable Annular Surface Pressure - MAASP, MASP Maximum Casing pressure that the formation can withstand prior to fracture = (EMW-MW)*0.052*TVD casing seat

10. Kick Tolerance Maximum ppg kick - Maximum mud weight increase on a kick prior to formation fracture =(EMW-MW)*TVD shoe /TVD well Assumes zero pit gain

11. Kick Tolerance Maximum Kick Volume

12. Kick Types Gas Kicks –Rapid expansion as gas circulated through choke –Mud gas separators and flare lines used –Gas migration problems –Higher SICP than others

13. Kick Types Gas Kicks, cont. –Barite settling in OB mud –Solubility of gas masks kick indicators –Flammability of gas –Slugging of gas at choke

14. Kick Types Oil Kicks –Flammable but not as explosive as gas –Density greater than gas-lower SICP –Very little expansion as kick reaches surface –But, there is almost always some gas present

15. Kick Types Water kicks –not flammable –very little expansion –lower SICP than gas or oil –But, there is still usually some gas present.

16. Kick Types Prediction kick types –Density of gas =1-2 ppg –Density of oil = 6-8 ppg –Density of salt water =8.6-9.0 ppg

17. Drillers Method Pressure at Top of Kick-P x

18. Drillers Method Surface Casing Pressure - CP –CP=P x -0.052*MW*x Pressure at casing seat - P seat –P seat =CP+0.052*MW*D seat –where the bubble is below the casing seat –P seat =P B -0.052*MW*(D-D seat ) –where the bubble is above the casing seat

19. Wait & Weight Method Pressure at Top of Kick-P x

20. Wait & Weight Method Surface Casing Pressure - CP –CP=P x -0.052*MW*x Pressure at casing seat - P seat –P seat =CP+0.052*MW*D seat –where the bubble is below the casing seat –P seat =P B -(0.052*MW*D’) –-[0.052*MW 1 *(D-D’-D SEAT )] –where the bubble is above the casing seat

21. Nomenclature

22. Examples

23. Surface Casing Pressure

24. Ann. Press @ Various Depths

25. Reaction of Gas in a Wellbore Boyle’s Law –PV=constant Charles’ Law –V/T=constant Avagadro’s Law –PV=nRT Real Gas Law –PV=ZnRT PV/ZT = nR P 1 *V 1 = P 2 *V 2 Z 1 *T 1 Z 2 *T 2 V 2 = P 1 *V 1 *Z 2 *T 2 P 2 *Z 1 *T 1

26. Reaction of Gas in a Wellbore Circulating gas from wellbore Given: –Depth=16,000’ –BHT =300 o F –BHP=12480 psi –MW=15.0 ppg –Surf. Temp =140 o F –Drilled up 1 cu.ft. of gas

27. Reaction of Gas in Wellbore

29. Gas Migration

30. MASP