- Since appraisal is a stage of intensive new data gathering, It is important to have a brief discussion on the type of samples that could be gathered for geochemistry analysis as well as geochemistry analytical programs. The main sample types for geochemistry studies could be grouped in three main categories: rocks, fluids, and solids. The rocks samples could be coming from source rocks or reservoir rocks and could be collected from whole cores, side-wall cores, cuttings, or outcrops. You could compare how source rock formation looks at an outcrop and as a whole core from a well at these two photographs. Also look at he sandstone reservoir rock recovered as a sidewall core from a well and as cuttings material. The fluid samples could represent petroleum seeps or slicks, fluid inclusions from reservoir rocks, mud gas while drilling a well, oil shows while drilling a well, rock cuttings or core extracts, produced oil, gas, or hydrogen sulfide. Here are several photos of different types of fluid samples that could be analyzed by geochemistry methods. Offshore oil slick. Onshore oil seep. Fluid inclusion in a reservoir rock. Note the scale of the 35 microns. Produced oil sample. The solid samples could be tar, asphalts at outcrops, or tar balls offshore, wax, asphaltenes, diamondoids, scale deposits. Here are several examples of petroleum solid samples. This is solid diamondoid deposit formed in a petroleum pipeline. And here is a tar ball washed onto California beach. A geochemistry study clarified tar ball originated from a Monterey Formation offshore seep. The source for this information and photo is from U.S. Geological Survey. Here's a photo of a scale deposit sample formed in producing oil well tubing. The scale deposit is a mix of inorganic and organic compounds including high molecular weight waxes.