Exercise 1 Introduction
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Dept. of Petroleum Eng. and Appl. Geophysics, NTNU Exercise 1: TPG5120 Petrophysics Basic Course. Hand in in shelves 2 nd floor by Aug. 27. Page 1 of 2 H. Langeland, NTNU Page 1 av 2 19.08.2004 Exercise 1: TPG5120 Petrophysics BC. Some rules and advices regarding exercises: Always try to understand what your are doing and why you are doing something in the exercises. Ask your fellow students, the student assistant the teacher… Exercises are to be delivered, and we do that on the second floor (Dept. office floor) where there are some shelves in the student area with the course number on – deliver your answer sheets there – stapled together. Mark the exercises clearly with the course name, exercise number and your name. If you don’t want to use all your middle names, always use your first and last name in that sequence. The exercises – when corrected – are returned in the same shelves where you handed them in. Look for them and ask about any errors you made if you don’t understand what you did wrong. 1. Measurements and parameters. a. How can you find indications of poreous and permeable zones in a well based on the caliper log? b. What is invasion, and how are the formations that we drill through influenced by invasion? c. And what do the following parameters relate to: R w , R t , R xo , R o , R m , R mf , φ ? d. What do S h , S xo , S w and S h mean, and what are the relations between these parameters? e. What petrophysical parameters do you think are the most important in determining the parameters in point d? List the parameters you think are important. 2. Hydrocarbon reserves. Calculate the amount of oil present in a reservoir covering an area of 40 km 2 and with an average thickness of 20 m. The average porosity is 0,2 and the water saturation is 0,3. Calculate in m 3 . How much oil may be recovered from this reservoir i we assume an average recovery factor (the fraction of oil that may be taken out) of 0,3. 2. Temperature evaluation: When we are comparing resistivities it is important that they all refer to the same temperature because the resistivity of a fluid varies with temperature. The temperature varies with depth in a well, and it also varies with time because the lower parts of the well are cooled down when the mud is circulated in the well as we drill (and upper parts of the well are heated by the warm mud from below). It is common to assume an approximate linear relationship between the temperature of the surface and the bottom hole temperature, BHT. In a well BHT is 110 o C at 5000 m, and the average surface temperature is 15 o C. Make an equation that interpolates linearly between the surface temperature and BHT and calculates a formation temperature, T f at 3000m. You may also find this by using Schlumberger Chart Gen-6 (attached).
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Exercise 1 Introduction
Transcript of Exercise 1 Introduction
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Dept. of Petroleum Eng. and Appl. Geophysics, NTNU Exercise 1: TPG5120 Petrophysics Basic Course. Hand in in shelves 2nd floor by Aug. 27. Page 1 of 2
H. Langeland, NTNU Page 1 av 2 19.08.2004
Exercise 1: TPG5120 Petrophysics BC.
Some rules and advices regarding exercises:
Always try to understand what your are doing and why you are doing something in the exercises. Ask your fellow students, the student assistant the teacher
Exercises are to be delivered, and we do that on the second floor (Dept. office floor) where there are some shelves in the student area with the course number on deliver your answer sheets there stapled together.
Mark the exercises clearly with the course name, exercise number and your name. If you dont want to use all your middle names, always use your first and last name in that sequence.
The exercises when corrected are returned in the same shelves where you handed them in. Look for them and ask about any errors you made if you dont understand what you did wrong.
1. Measurements and parameters.
a. How can you find indications of poreous and permeable zones in a well based on the caliper log?
b. What is invasion, and how are the formations that we drill through influenced by invasion?
c. And what do the following parameters relate to: Rw , Rt , Rxo , Ro , Rm , Rmf , ? d. What do Sh , Sxo , Sw and Sh mean, and what are the relations between these parameters?
e. What petrophysical parameters do you think are the most important in determining the parameters in point d? List the parameters you think are important.
2. Hydrocarbon reserves.
Calculate the amount of oil present in a reservoir covering an area of 40 km2 and with an average thickness of 20 m. The average porosity is 0,2 and the water saturation is 0,3. Calculate in m3.
How much oil may be recovered from this reservoir i we assume an average recovery factor (the fraction of oil that may be taken out) of 0,3.
2. Temperature evaluation:
When we are comparing resistivities it is important that they all refer to the same temperature because the resistivity of a fluid varies with temperature. The temperature varies with depth in a well, and it also varies with time because the lower parts of the well are cooled down when the mud is circulated in the well as we drill (and upper parts of the well are heated by the warm mud from below).
It is common to assume an approximate linear relationship between the temperature of the surface and the bottom hole temperature, BHT.
In a well BHT is 110 oC at 5000 m, and the average surface temperature is 15 oC. Make an equation that interpolates linearly between the surface temperature and BHT and calculates a formation temperature, Tf at 3000m. You may also find this by using Schlumberger Chart Gen-6 (attached).
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Dept. of Petroleum Eng. and Appl. Geophysics, NTNU Exercise 1: TPG5120 Petrophysics Basic Course. Hand in in shelves 2nd floor by Aug. 27. Page 2 of 2
H. Langeland, NTNU Page 2 av 2 19.08.2004
3. Temperature adjustment of resistivity values.
Some resistivities are measured under surface temperature conditions, f.ex. the resitivity of the mud, Rm , of mud filtrate, Rmf and the mudcake, Rmc . Most resitivities are measured downhole by sondes. Resistivities of fluids changes with temperature, and must be corrected to the same temperature level when you want to make calculations. At 20 oC Rmf = 0.45 ohm~m. What is the resistivity at 3000 m under the same conditions mentioned in point 2?
