Changes

* Pump pressure

* Pump pressure

* Jet nozzle size(s) of the bit

* Jet nozzle size(s) of the bit

* Mud rheology (plastic viscosity and yield point)

* Mud rheology (plastic [[viscosity]] and yield point)

* Mud weight and effective circulation density

* Mud weight and effective circulation density

* Formation balance gradient (mud weight required to equalize formation pressure)

* Formation balance gradient (mud weight required to equalize formation pressure)

===Visual stain===

===Visual stain===

Staining of the drill cuttings by oil is an indication that hydrocarbons have been in the formation at some point in time. The lack of sample staining, however, does not prove that a reservoir lacks producible hydrocarbons. The amount and distribution of staining is a function of the reservoir porosity and permeability. Stain color can be related to oil gravity, with darker staining indicating heavier hydrocarbons. If a stained sample does not fluoresce or cut, then this indicator is classified as thermally “dead oil” and is not considered a show. Staining is described in terms of its color, distribution, percentage of sample stained, and fluorescence (if any).

Staining of the drill cuttings by oil is an indication that hydrocarbons have been in the formation at some point in time. The lack of sample staining, however, does not prove that a reservoir lacks producible hydrocarbons. The amount and distribution of staining is a function of the reservoir porosity and permeability. Stain color can be related to oil [[gravity]], with darker staining indicating heavier hydrocarbons. If a stained sample does not fluoresce or cut, then this indicator is classified as thermally “dead oil” and is not considered a show. Staining is described in terms of its color, distribution, percentage of sample stained, and fluorescence (if any).

===Fluorescence===

===Fluorescence===

| colspan = 2 align = center | ''' Minerals'''<ref name=pt03r17 />

| colspan = 2 align = center | ''' Minerals'''<ref name=pt03r17 />

|-

|-

| Dolomite, magnesian limestones || Yellow, yellowish brown to dark brown

| [[Dolomite]], magnesian limestones || Yellow, yellowish brown to dark brown

|-

|-

| Aragonite and calcareous mudstones || Yellow-white to pale brown

| Aragonite and calcareous mudstones || Yellow-white to pale brown

| Foliated shales || Tan to grayish brown

| Foliated shales || Tan to grayish brown

|-

|-

| Anhydrite || Blue to mid-gray

| [[Anhydrite]] || Blue to mid-gray

|-

|-

| Pyrite || Mustard yellow to greenish brown

| Pyrite || Mustard yellow to greenish brown

[[Category:Wellsite methods]]

[[Category:Wellsite methods]]