Changes

| [[Porosity]] and permeability trends are controlled by clay diagenesis or secondary cements || Determine the petrological and mineralogical history of reservoir facies; identify and map “diagenetic facies” relative to sedimentary facies

| [[Porosity]] and permeability trends are controlled by clay diagenesis or secondary cements || Determine the petrological and mineralogical history of reservoir facies; identify and map “diagenetic facies” relative to sedimentary facies

|-

|-

| Reservoir gas accumulations lack a floored gas-water contact || Map structural, isothermal, and pressure gradient contours that are likely coincident with boundaries of the gas envelope<ref name=pt06r113>Rose, P. R., Everett, J. R., Merin, I. A., 1986, [http://archives.datapages.com/data/specpubs/resmi1/data/a066/a066/0001/0100/0111.htm Potential basin-centered gas accumulation in Cretaceous Trinidad Sandstone, Raton Basin, Colorado] in Spencer, C. W., Mast, R. F., eds., Geology of Tight Gas Reservoirs: AAPG Studies in Geology Series 24, p. 111–128.</ref>

| Reservoir gas accumulations lack a floored [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=gas-water+contact gas-water contact] || Map structural, isothermal, and pressure gradient contours that are likely coincident with boundaries of the gas envelope<ref name=pt06r113>Rose, P. R., Everett, J. R., Merin, I. A., 1986, [http://archives.datapages.com/data/specpubs/resmi1/data/a066/a066/0001/0100/0111.htm Potential basin-centered gas accumulation in Cretaceous Trinidad Sandstone, Raton Basin, Colorado] in Spencer, C. W., Mast, R. F., eds., Geology of Tight Gas Reservoirs: AAPG Studies in Geology Series 24, p. 111–128.</ref>

|-

|-

| Overpressured formation or reservoir (occurs frequently due to common distribution of tight gas with basin center locations and excessive overburden) || Requires appropriate exploration strategies or reservoir engineering approach to gas recovery

| Overpressured formation or reservoir (occurs frequently due to common distribution of tight gas with basin center locations and excessive overburden) || Requires appropriate exploration strategies or reservoir engineering approach to gas recovery

* Have the core analyses (porosity and permeability) data in hand while observing the core to determine the relative effect of the features observed (see [[An overview of routine core analysis]]). Obtain three-dimensional whole-core analyses, if possible, when the fractures or other anisotropic features are predicted to be important.

* Have the core analyses (porosity and permeability) data in hand while observing the core to determine the relative effect of the features observed (see [[An overview of routine core analysis]]). Obtain three-dimensional whole-core analyses, if possible, when the fractures or other anisotropic features are predicted to be important.

* Create the fracture stratigraphy (involves steps 5 through 16).

* Create the fracture stratigraphy (involves steps 5 through 16).

* Construct a core deformation strip log at a relevant scale that includes the positioning of major lithology and formation breaks, lost core and noncored intervals, oil-water or gas-water contacts (if available), fractures, and stylolites. Hairline fractures in the core are often difficult to see. These can be enhanced by painting the core with a volatile liquid and observing the drying pattern. Overlooked fractures may “jump out” at the observer by persistence of wetting along hairline fractures reaching the core surface. Additional characterization of hairline or larger fractures internal to the core can be accomplished by core X-radiographs or core computer tomography scans.

* Construct a core deformation strip log at a relevant scale that includes the positioning of major lithology and formation breaks, lost core and noncored intervals, [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=oil-water+contact oil-water]  or [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=gas-water+contact gas-water contacts]] (if available), fractures, and stylolites. Hairline fractures in the core are often difficult to see. These can be enhanced by painting the core with a volatile liquid and observing the drying pattern. Overlooked fractures may “jump out” at the observer by persistence of wetting along hairline fractures reaching the core surface. Additional characterization of hairline or larger fractures internal to the core can be accomplished by core X-radiographs or core computer tomography scans.

* Record the fracture distribution with depth ([[:file:evaluating-fractured-reservoirs_fig2.png|Figure 2]]). (Recording of this and all following data could be done in a tabular format compatible with computer entry to facilitate output compatible with other strip and well logs.)

* Record the fracture distribution with depth ([[:file:evaluating-fractured-reservoirs_fig2.png|Figure 2]]). (Recording of this and all following data could be done in a tabular format compatible with computer entry to facilitate output compatible with other strip and well logs.)

* Relate fracture distribution to rock type.

* Relate fracture distribution to rock type.