Sources of Data - LAS converter menu

Apart from core data and petrographic data such as point counted data from thin sections (TS), wireline logging data is a key input. Many people in the oil industry think that this is reliable and cheap data. Nothing is farther from the truth. Wireline logs are typically stored in LAS files. The extension LAS stands for Log ASCII Standard.? This is basically a text file where wireline data is stored in a specific standard format defined by the Canadian Well Logging Society. There are two common versions 1.2 and 2.0. Currently there is also work done on a version 3.0.

Curve 3.0 uses an ASCII Standard file for core analysis and description data called ‘CAS’. Hmmm, very original name. We will discus these files with extension ‘.CAS’ later on. They form a critical part of Curve and allow detailed interaction between wire line log response and mineralogical, porosity, and permeability data obtained from detailed core and petrographic data. We also plan detailed examination of log response versus Capillary pressure analysis data.

LAS files (extension: las) are rented or owned by companies in the oil industry such as oil and gas companies or by industry consulting companies such as Eucalyptus, etc.? This data is generated by these companies in house, most often through data digitizing or petrophysical analysis (log analysis).? Also, there are several data provided by companies such a GeoLOGIC, IHS, MJs, Petro Ninja, and digitizing services, Wireline logging Companies such as Schlumberger and by forever name changing Alberta Government agencies AER formerly EUB, or ERCB (if I remember correctly).?? The latter is the public domain data collector of well data from which most data providers extract their data and convert them into appropriate data formats and then claim its ownership.

IHS and Geologic mostly rent this data to industry. Petro Ninja provide clients the ownership of the data but also, it is least processed and, in a format, similar to the database of the AER. This latter data needs a considerable amount of data processing by the downloading client (Oil and Gas companies, consultants) but is in our opinion cheapest.? Software such as AccuMap provided by companies like IHS, is used mostly on a rental basis. The big disadvantage of the rented data is that upon changing data provider this data must be removed from the client’s computer and data storage systems which may destroy a client’s mapping and analysis results. Especially when processed in software such as Geographix and Petra. MJs offers LAS data and Raster images both for sale and rent and is of good Quality. Also digitizing services offer decent LAS data for sale.

In our experience, you get what you pay for. IHS-data is of the highest quality and completeness (most wells in its database). GeoLOGIC data, similar to IHS, but is significant poorer quality (in our opinion), although we haven’t used GeoLOGIC for a number of years and they may have improved. ?PetroNinja data is cheapest and poorest, mostly as downloaded from the EUB and incomplete. Digitizing Services are great for supplementing incomplete LAS data and of good quality.

CURVE 3.1.0. stores LAS data in its LAS RAW directory. The data is converted into EUCALYPTUS data and saved in LAS version 2 files, after which is stored in the commonly named LAS IN directory (INDIR). The original LAS data is converted into a single well las file where curves have a BIT curve and TEMP curve added; all curves are resampled to a 0.10m depth increment plus it is converted into consistent measurement units (V/V for porosity curves, gm/m3 for density types of logs, API for gamma ray types of logs). All logs are rated using an ALIAS file with over 3000 curve acronyms or mnemonics. The alias files used by CURVE have been carefully inspected and the program ?creates files of missing acronyms that may be, later, permanently included in the alias file. The LAS files in the INDIR, often named LAS IN, retain their original curve names referred to as AKAs. Once normalized, processed, or created through CURVE, they are renamed according to CURVE standard names (the alias names) and are stored into the OUTDIR.? So, DENS and RHOB curves are renamed RHOB. All acoustic and sonic logs are referred to DT, etc.? LAS files are created for each well and stored in the OUTDIR (often named LAS OUT). This directory also contains calculated curves such as SW_FN or POR_FN or VCLY_FN. The CURVE analyst has finally the option to select preferred curves and store them in LAS CLIENT for third party clients or for use by non-petrophysical staff in-house. This provides lots of flexibility in the processing and delivery of the original RAW delivered curves and a consistent data output of data processed by CURVE 3.0

The tools menu helps to manipulate or remove many curves within individual LAS files or to altercurve over the entire project. It also helps with the selection and management of well lists (text files with extension '.wzn'.

Many data providers deliver data in inconsistent data units and depth increments.? This data, especially radiation logs such as Neutron logs and Gamma Rays need first to be converted in API units (GR) or PU or V/V (fractions) and then to be ‘normalized’ i.e. rescaled to a consistent log response throughout the project. Upon normalization, such logs are stored in the OUTDIR (typically LAS OUT directory) with the curve name extension ‘_NRM’, example: ‘GR_NRM’ or NPHI_NRM, etc.

In the RAW DIR, logs can be very confusing. For example, a well can have multiple LAS files recorded over different depth intervals, requiring depth corrections. They may be measured in imperial feet or in metric with different depth increments even in the same well.? Their measurement units may differ, and some may be ‘main pass’ while others are ‘repeats’. Once ‘cleaned’ they are stored in the INDIR (LAS IN). Depending on the quality of your data provider you may spend considerable time ‘cleaning up’. And time is money.

When the LAS files are cleaned up, normalized, or approved for use in calculations or derived from scripts or other calculations. Subsequently, they are stored with standard curve names (GR, SW, PERM, etcetera) in the OUTDIR. Cleaning data for use in the OUTDIR ready for analysis may take up to 60% of a petrophysicist’s workload. CURVE 3.0 has a lot of this clean-up work automated. When adding core description and measured data through our special ‘.CAS’ files the data inout is quite extensive and time demanding – See the ‘Lithology’ menu

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