Changes

==GOM basin example==

==GOM basin example==

In the GOM basin, variations in well-log response and biofacies distribution are analyzed for recognition of stacked depositional sequences. The [[Basic open hole tools#Gamma ray|gamma-ray]] log display provides a measure of sediment type, with curve deflections to the left suggesting increased sand content while high values to the right indicate increases in clay content. Use of multiple logs, especially [[Basic open hole tools#Spontaneous potential|spontaneous potential]], resistivity, density, and velocity logs calibrated by well-cutting descriptions and formation microscanner displays, provides a data set for reliable rock type identification. The figure below illustrates an interpretation template for log motif analysis.

In the GOM basin, variations in well-log response and biofacies distribution are analyzed for recognition of stacked depositional sequences. The [[Basic open hole tools#Gamma ray|gamma-ray]] log display provides a measure of sediment type, with curve deflections to the left suggesting increased sand content while high values to the right indicate increases in clay content. Use of multiple logs, especially [[Basic open hole tools#Spontaneous potential|spontaneous potential]], [[Basic open hole tools#Resistivity|resistivity]], density, and velocity logs calibrated by well-cutting descriptions and formation microscanner displays, provides a data set for reliable rock type identification. The figure below illustrates an interpretation template for log motif analysis.

Patterns of forestepping vs. backstepping log-motif funnels can define transgressive vs. regressive depositional trends and candidate systems tracts and sequences. Vail and Wornardt<ref name=ch04r101>Vail, P., R., Wornardt, W., W., 1990, Well log seismic stratigraphy: a new tool for exploration in the '90s: Proceedings, Gulf Coast Section SEPM 11th Annual Research conference, p. 379–388.</ref> and Armentrout et al.<ref name=ch04r8>Armentrout, J., M., 1993, Relative seal-level variations and fault-salt response: offshore Texas examples: Proceedings, Gulf Coast Section SEPM 14th Annual Research Conference, p. 1–7.</ref> detail the process.

Patterns of forestepping vs. backstepping log-motif funnels can define transgressive vs. regressive depositional trends and candidate systems tracts and sequences. Vail and Wornardt<ref name=ch04r101>Vail, P., R., Wornardt, W., W., 1990, Well log seismic stratigraphy: a new tool for exploration in the '90s: Proceedings, Gulf Coast Section SEPM 11th Annual Research conference, p. 379–388.</ref> and Armentrout et al.<ref name=ch04r8>Armentrout, J., M., 1993, Relative seal-level variations and fault-salt response: offshore Texas examples: Proceedings, Gulf Coast Section SEPM 14th Annual Research Conference, p. 1–7.</ref> detail the process.