The SP's Kick Ass Hacks

A blog that explains petrophysics in the way we all can understand. Contains petrophysical hacks that get you ahead the curve.

RCA vs SCAL

From RCA you get grain density, porosity and permeability. From SCAL you get the electrical parameters (m,n), capillary curves and relative permeability.

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Generate missing sonic log using resistivity logs with this transform

In many older fields, you only have resistivity logs to work with. What if you need a sonic log to generate seismic seismogram? A quick solution is to generate your own pseudo sonic log. (image source: borrachas.tumblr.com) In 1951, Faust came up with a transform to estimate compressional...

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The 'X-Ray' trick to estimate density-neutron porosity

Do you know that you can visually estimate porosity just by looking at your density and neutron logs? The trick is very simple, but not a lot of people know about it. It’s particularly useful in a relatively clean carbonate or sandstone and liquid (oil or gas) bearing zone. So, here is the...

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Patterns and trends: A sure and a quick way to evaluate a reservoir.

Petrophysicists like patterns and trends. It’s a sure and a quick way to evaluate a reservoir. They make it easier for us to establish, correlate and predict the outcomes. Like in a quick log analysis, if we know that the density-neutron are overlaying, it means that we are in an oil or water...

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Is wireline depth always deeper than the LWD depth?

Is wireline depth always deeper than the LWD depth? In most cases, the wireline depth is deeper than the LWD Depth. The cable stretches more than the pipe stretch of LWD string. But the good thing is, the cable stretch can be corrected, while the LWD stretch cannot be corrected. The first...

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The Three Things You Need To Be Good At When Interpreting Logs

There are three things you need to be good at log interpretation: Identify, Interpret and Integrate. 1. Identify Have an interest in what, why and how of the things you do. For instance, if you want to interpret a log, you need to know why you spend money to get the logs, how to tell good...

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Rock Typing In Complex Carbonates. Which One Do You Choose?

Diagenesis makes complex carbonate complex. Classifying the rock types in any complex carbonate reservoirs is very hard. Rock typing is a clustering of rocks that have the similar geological and petrophysical properties at core and log scale. It's like trying to group your rock favorite rock...

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Got a shale gas reservoir? Evaluate these four parameters and you are good to go.

When you evaluate a shale gas reservoir, you need to think about four things: Kerogen contents Kerogen is one the key properties in shale gas evaluation. Kerogen relates to TOC, absorbed gas, porosity and gas saturation. Most unconventional reservoirs like shale oil and shale gas contains...

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The Three Main Problems With Petrophysical Data

The are three main problems with petrophysical data: 1. Too much data 2. Too little data 3. Bad data We'll just have to deal with it, one step at a time.

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Do You Need Kerogen Correction In Resistivity For Shale Oil/Shale Gas Evaluation?

When kerogen and shales are present, you must apply a shale and kerogen correction to get effective porosity. While we can correct for shale effect in resistivity, do we need to worry about making kerogen correction for resistivity and water saturation? Is there a kerogen correction we must...

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