GP 202 Reservoir Geomechanics

Spring 2014, OpenEdX

Homework 1 Calculating Overburden Stress

SOLUTIONS Click the right tab on the top of the page to download the solutions data

Part 1: Compute the overburden stress and overburden gradients

a. Plot density vs. depth for each dataset. b. Divide the density profiles into 5 blocks.

c. Calculate the overburden stress.

d. Calculate the overburden gradient (overburden stress normalized by depth).

Part 2: Compute porosity from density logs

a. Compute porosity assuming complete saturation and hydrostatic pore pressure. b. Plot porosity vs. depth for each dataset.

Part 3: Answers to Homework 1 Questions

Question 1: Density Profiles

a. What is the logged density in the Barnett Shale well at 5000 ft depth in g/cc? = 2.4061 +/- 0.24061 g/cc

b. What is the logged density in the Gulf of Mexico well at 5000 ft depth in g/cc? = 2.1640 +/- 0.21640 g/cc

Question 2: Overburden Stress Profiles

a. What is the overburden stress in the Barnett Shale well at 5000 ft depth in SI units (MPa)?

= 38.5731 +/- 3.85731 MPa

b. What is the pore pressure in the Barnett Shale well at 5000 ft depth in SI units (MPa)?

= 15.24 +/- 1.524 MPa

c. What is the overburden stress in the Gulf of Mexico well at 5000 ft depth in SI units (MPa)?

= 29.4635 +/- 2.94635 MPa

d. What is the pore pressure in the Gulf of Mexico well at 5000 ft depth in SI units (MPa)?

= 15.24 +/- 1.524 MPa

Question 3: Overburden Stress Gradient Profiles

a. What is the overburden stress gradient in the Barnett Shale well at 5000 ft depth in SI units (MPa)?

= 25.3104 +/- 2.53104 MPa/km

b. What is the overburden stress gradient in the Gulf of Mexico well at 5000 ft depth in SI units (MPa)?

= 19.3330 +/- 1.93330 MPa/km

Question 4: Porosity Profiles

a. What is the porosity in the Barnett Shale well at 2500 ft depth? = 0.0292 +/- 0.0292

b. What is the porosity in the Gulf of Mexico well at 10000 ft depth? = 0.1976 +/- 0.0988