Reservoir Geomechanics: Stress Measurement Techniques

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What is the definition of stress according to the text?

A force acting over a given area (correct)

A tensor that describes the density of forces acting on all surfaces passing through a given point

A measure of the deformation of a material

The resistance of a material to an applied force

What are the two main types of geological activity that occur because of plate tectonics?

Volcanoes and earthquakes

Erosion and sedimentation

Uplift and subsidence

Mountain building and earthquakes (correct)

Which type of stress is most common at convergent plate boundaries?

Shear stress

Confining stress

Tension stress

Compression stress (correct)

What is the primary purpose of measuring, estimating or constraining stress magnitudes at depth in oil, gas and geothermal reservoirs?

To address a wide range of problems in reservoir geomechanics Signup and view all the answers

What is the relationship between plate tectonics and the four types of stresses acting on materials?

Plate tectonics causes all four types of stresses to act on materials Signup and view all the answers

What is the main purpose of describing stresses acting on a homogeneous, isotropic body at depth as a second-rank tensor?

To capture the directional and magnitude information of the stress field Signup and view all the answers

What type of fold is characterized by the oldest rocks at the center and the youngest at the outside?

Anticline Signup and view all the answers

In which type of fault do rocks crumple into folds and deform plastically under compressive stresses?

Reverse fault Signup and view all the answers

What is the relative distance that rocks move along a fault called?

Slip Signup and view all the answers

What type of fold results in rocks arching upward and dipping away from the center of the fold?

Anticline Signup and view all the answers

Which type of fault has blocks of rock on one or both sides moving due to a fracture?

Joint fault Signup and view all the answers

What type of structure is characterized by rocks bending downward in a circular manner?

Monocline Signup and view all the answers

What is the most common type of stress at convergent plate boundaries?

Compression Signup and view all the answers

What happens to rocks under tension?

They lengthen or break apart Signup and view all the answers

What is the major type of stress at divergent plate boundaries?

Tension Signup and view all the answers

What happens when forces are parallel but moving in opposite directions?

Shear Signup and view all the answers

What is the most common type of stress at transform plate boundaries?

Shear Signup and view all the answers

What is the relationship between stress and strain?

Stress causes deformation, and the amount of deformation is called strain Signup and view all the answers

What type of rocks are considered 'incompetent' in the text?

Shale and evaporites Signup and view all the answers

What feature on a map or cross-section indicates a 'ramp' portion of a fault?

The fault cuts stratigraphic boundaries at a high angle Signup and view all the answers

What is the purpose of 'section balancing' according to the text?

To match footwall and hanging wall cutoffs on the same fault Signup and view all the answers

What feature on a map or cross-section indicates a 'flat' portion of a fault?

The fault surfaces are almost parallel to the stratigraphic boundaries Signup and view all the answers

What is the meaning of the term 'décollement' according to the text?

A very extensive flat where there has been a large amount of movement Signup and view all the answers

What is the Humber Arm Allochthon composed of according to the text?

Cambrian and Ordovician deep-water sedimentary rocks and ophiolites Signup and view all the answers

What type of deformation occurs when a rock returns to its original shape after the stress is removed?

Elastic deformation Signup and view all the answers

Which of the following factors does NOT affect a rock's response to stress?

Color of the rock Signup and view all the answers

Where in the Earth's crust are rocks more likely to undergo plastic deformation?

Deeper in the crust Signup and view all the answers

What is the typical orientation of sedimentary rock layers when they are first formed?

Horizontal Signup and view all the answers

What type of deformation occurs when a rock under stress breaks?

Fracture deformation Signup and view all the answers

What is the significance of sedimentary rock layers that are not horizontal?

They suggest the rock has been deformed in some way Signup and view all the answers