Rock Compressibility

Compressibility is a relative volume change of a fluid or solid in a response to a pressure change. We can relate this into a reservoir engineering aspect. Overburden pressure is rock weight and it typically has a gradient of 1 psi/ft. Rock metric and formation fluid in pore spaces supports the weight of rock above. When petroleum is produced from reservoir rocks, pressure of fluid in pore space decreases, but overburden is still the same. This will result in the reduction of bulk volume of rock and pore spaces. The reduction on volume in relation to pressure is called “pore volume compressibility (cf)” or “formation compressibility” and it can be mathematically expressed like this.

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Transform Organic Matter into Petroleum

This article will explain the overall of how to transform organic matter into petroleum. Chemical processes will take place in order to transform organic matter preserved in source rocks into petroleum. This can be called a cooking process. Three phases regarding maturation of the organic matter to form petroleum are diagenesis, categenesis and metagenesis.

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Organic Matter to Form Source Rock

Oil and gas that we are drilling today comes from a biogenic origin and it is formed with proper time and temperature. Organic matter is one of the most important parts of hydrocarbon generation. This topic will give you an overview of how organic matter will be transformed to hydrocarbon.


Starting with plants and algae, take carbon (CO2) from the atmosphere and process it to form glucose and this starting process is called photosynthesis. Glucose is transformed into more complex organic compounds. Trees, for example will grow bigger because they use photosynthesis to convert into energy. When animals and trees die, the organic matter is typically oxidized and this will create CO2 and put water back into environment again.  However, in some situations when organic matter is buried quickly in areas where there is no oxygen, the organic matter may be preserved. If the organic matters are buried in proper conditions, petroleum may be formed. Continue reading