Changes

==Outcrop analysis==

==Outcrop analysis==

When collecting [[fracture]] data from outcrops, one should look for rocks similar to the reservoir rocks of interest on similar outcropping structures. Look at more of the rock section than just the prospective reservoir rock, including potential sealing beds, and pay attention to relative fracture intensity between layered units.

When collecting [[fracture]] data from outcrops, one should look for rocks similar to the [[reservoir]] rocks of interest on similar outcropping structures. Look at more of the rock section than just the prospective reservoir rock, including potential sealing beds, and pay attention to relative fracture intensity between layered units.

* Select outcrop areas having representative fracture patterns for specific structural positions. Record strike and dip data, or at least strike data. Additional sites can be chosen for one unit at different positions within the structure.

* Select outcrop areas having representative fracture patterns for specific structural positions. Record [[strik]]e and [[dip]] data, or at least strike data. Additional sites can be chosen for one unit at different positions within the structure.

* For a so-called quantitative measurement station (having enough fracture measurements to be statistically meaningful), all fractures in the measurement area should be recorded and should number from about 100 to 150 fractures. The actual number should depend on the complexity of the fracture patterns present.

* For a so-called quantitative measurement station (having enough fracture measurements to be statistically meaningful), all fractures in the measurement area should be recorded and should number from about 100 to 150 fractures. The actual number should depend on the complexity of the fracture patterns present.

* For a so-called qualitative measurement station (not having enough fracture measurements to be statistically meaningful), only general fracture trends are recorded, along with a judgment of relative abundance of the individual fracture orientations. These are often used when spot checking areas between statistical measurement stations. If no major change in orientation and intensity of fracture patterns is observed away from nearby statistical measurements stations, the use of qualitative stations gives valid intermediate data.

* For a so-called qualitative measurement station (not having enough fracture measurements to be statistically meaningful), only general fracture trends are recorded, along with a judgment of relative abundance of the individual fracture orientations. These are often used when spot checking areas between statistical measurement stations. If no major change in orientation and intensity of fracture patterns is observed away from nearby statistical measurements stations, the use of qualitative stations gives valid intermediate data.

* At the individual measurement stations, the analyst should record as much of the following information as possible.<ref name=pt06r95 />

* At the individual measurement stations, the analyst should record as much of the following information as possible.<ref name=pt06r95 />

* Each individual fracture measurement at the station should record as much of the following data as possible (see <ref name=pt06r95 />).

* Each individual fracture measurement at the station should record as much of the following data as possible (see <ref name=pt06r95 />).

* At convenient times, the fracture data should be plotted in preliminary form on either rose diagrams or pole plots (π diagrams). Such preliminary plotting is necessary in the field to establish trends and application to simple geological fracture models. In this way, working interpretive models can be created and altered or updated while field data are still being gathered. The observer should always examine fracture patterns in light of their relationship to their localities and to local structural configuration.

* At convenient times, the fracture data should be plotted in preliminary form on either [ht tp://www.answers.com/topic/rose-diagramrose diagrams] or [facstaff.uww.edu/bhattacj/geolgy318_presentation_2.ppt pole plots (π diagrams)]. Such preliminary plotting is necessary in the field to establish trends and application to simple geological fracture models. In this way, working interpretive models can be created and altered or updated while field data are still being gathered. The observer should always examine fracture patterns in light of their relationship to their localities and to local structural configuration.

* The number and frequency or spacing of quantitative measurement stations are generally high in the early stages of study in a region and decrease in relationship to qualitative stations throughout the study.

* The number and frequency or spacing of quantitative measurement stations are generally high in the early stages of study in a region and decrease in relationship to qualitative stations throughout the study.

* When dealing with outcrops containing a predominance of either contractional fractures or fractures related to unconformity surfaces,<ref name=pt06r95 /> much of the previous quantitative orientation data will be ill-defined due to their isotropic or irregular distribution in orientation. In these outcrops, matrix block size (fracture spacing in three dimensions) are very important, as are lateral distribution and lithology.

* When dealing with outcrops containing a predominance of either contractional fractures or fractures related to [[unconformity]] surfaces,<ref name=pt06r95 /> much of the previous quantitative orientation data will be ill-defined due to their [http://www.merriam-webster.com/dictionary/isotropic isotropic] or irregular distribution in orientation. In these outcrops, matrix block size (fracture spacing in three dimensions) are very important, as are lateral distribution and lithology.

* Photograph all outcrops measured and take block samples (about 10” × 6” × 5”) of all major units of interest for petrophysical and possibly mechanical testing.

* Photograph all outcrops measured and take block samples (about 10” × 6” × 5”) of all major units of interest for petrophysical and possibly mechanical testing.