Log Type Log Name Curve Characteristics Interpretation Lithology Logs Gamma Ray & Spontaneous Potential (SP) Deflection to the right Shale Deflection to the left Sand Resistivity Logs Deep Resistivity High Hydrocarbons Tight Streaks Low porosity Low Shale Wet Sand Separation between the resistivities Formation and drilling fluids are different Formation is permeable Porosity Logs Density … Continue reading Short Cut Interpretation
Tag: Logging
Micro-Resistivity
These logs are capable of detecting formations less than 1.0in. thick, if the mud cake is very thin. Micro-laterologs can be used in salt muds and high resistivities. Their response will be affected by mud cake greater than 3/8" thick. Typically used to measure Rxo and determine permeable beds by detecting mudcake. Limitations Shallow invasion … Continue reading Micro-Resistivity
Short Spaced Resistivity
Short Normal The usefulness of the curve will be determined by the vertical resolution. The short normal (SN) is useful as long as the contrasts between the drilling fluid and formation resistivities are not too great. Resistivity beds will appear thinner by the arm spacing (16ins.), and conductive beds appear thicker by the same amount. … Continue reading Short Spaced Resistivity
Gamma Ray
Measures the natural resistivity of the formations in the borehole. Good for the identifying lithology and correlation purposes. The GR log usually reflects the shale content of the formations because of the concentrations of radioactive materials in the shales/clay. Shale free sandstones and carbonates have low gamma ray values unless contaminants are present. They are … Continue reading Gamma Ray
Spontaneous Potential (SP)
Spontaneous Potential (SP) This is a record of the direct current voltage differences between the naturally occurring potential maintained by a movable electrode in the borehole and a fixed potential located at the surface. The potential is as a result in the difference between the salinity of the drilling and formation fluid. The SP log … Continue reading Spontaneous Potential (SP)
Porosity Logs
Sonic Log Essentially it emits a sound pulse and has a receiver that picks up the sound pulse as it passes the receiver. This produces a transit time and generates a wave form that can be interpreted. In the sonic log the velocity of the wave form through the rock matrix will help to determine … Continue reading Porosity Logs
Intro To Logging
Introduction The logging of a well bore is the process of measuring the electrical resistivity of the surrounding formation and the fluids within. It is known that the electrical resistivity of rock is high however the resistivity of minerals and fluids that occupy the pore spaces of said rock have proven to be low in … Continue reading Intro To Logging
Reservoir Evaluation (Intro)
This section will be a brief introduction into the methods used to evaluate the well bore environment, the formations drilled and the formations beyond the wellbore. Typically this is done to better the operators’ knowledge base and understanding of the formations it encounters, build a better model of the drilling environment which in turn helps … Continue reading Reservoir Evaluation (Intro)