Freelance Gephysical Consultants Ltd



INTERNET REMOTE QC SERVICES

We can check and QC you daily acquired seismic data remotely. We can make available a fast UPLOAD INTERNET DROP BOX. Afterwards,we can give you a quick turn around in less than 24 hours.
you can give us your data for field QC processing, such as:

    * Survey Raw Data SPS and P190 navigation data.

    * Land or Marine seismic recording instruments for analysis.

    * Pelton Vibroseis Data Analysis and results.

    * Trimble, Leica and Thales RAW DGPS data for processing.

    * DSD Extended SEG-D file from Sercel VE464.

    * Daily Acquired land or marine SEG-D data for signal-to-noise ratio analysis, frequency analysis, leakage, resistance and tilt errors, etc. Whatever our client request to be done on his data.

    * Sercel VE432/464 aps, vaps, cog and raw data for cycle time analysis and error detections on a daily acquisition up to 30 vibrators in production on a high density channel crew.

    * Sercel eSQC-pro ADS data for analysis in a daily basis.

    * Pre-plot and Post-plot survey data in SP1 or SPS data format for position accuracy.

    * Survey Raw Data SPS and P190 navigation data.

    * Final SEG-Y filtered or unfiltered data to render 3D volumes.

    * Daily QC processing of whatever data is necessary to be checked in due time to make a decision, such as infill or re-shoots.

    * Random SEG-D files to be checked on the auxiliary traces for proper polarity, predicted time break, field time break, uphole times and water breaks in case of marine data.

    * Technical Report Writing and proof reading.

    * Acoustic OBC or deep marine positioning P2 data for analysis.

    * Any analysis to be done on a marine P2 raw data versus final P1 UKOOA file and discrepancies.

    * Tender Bid preparations and evaluations.

    * Airgun Synchonizer or SeaMap Gunlik data analysis for timing accuracy.

    * Manpower to QC land, OBC, deep marine, heliportable, explosives and TZ land crews and at the most reasonable and fair daily rate in the market. If TNT is to be used,
    ,we suggest whether to use low velocity or high velocity explosives" TNT" depending on your targets. Nobody uses dynamite in seismic acquisition. It has been widely wrong used, but dynamite is highly unstable. Also we remind our customers about the lifetime and proper storage of TNT, temperature and how to avoid TNT sweating and loosing its penetration power.

    * Interpretation services using Petrel, Kingdom Suite, VoxelGeo, Charisma Geoframe or WinPICS.

We offer many more services, regarding technical daily QC data, also GIS data and quick resolution satellite images, examination of any 3D survey design and possible footprints and how to avoid the footprints and get th best to illuminate most of the worldwide Oil Companies target depths. In the 21st century, using the proper tools , software, hardware and afficient manpower brain, it is quite hard to drill a dry well using our expertise.


SAMPLE VIBROSEIS ANALYSIS

THE SAMPLE DATA IS FROM TWELVE VIBRATORS, FOUR FLEETS OF 3 VIBRATORS EACH FLEET USING WIDE AZIMUTH SURVEY WAS=1.5

Be careful with vibrator with more than 8 years of age, could have mechanical wearing, fatigue and deterioration, the servo mechanismm and the electronics are essentil to be in good shape. We make sure that the following is in place:
low and high pressure values, Cracks on base plate - top plate : It is visual inspection, crack is at origin of distortion when the signal of the base plate accelerometer is noisy. We can also see it on FTT graph, you will see noise between main harmonic. We can analyze SEG-D extended DSD QC file, or sandwich box file for you.


Hydraulic pressure : To insure good sweep quality, it is very important to have : vibration pressure at 220 bars. lift pressure at 135 bars. Vibration low pressure at 20 bars (if too high no good because the hydraulic force = vib pressure minus low pressure).
If the problem is the pressure, we could do static check but you could have intern leakage during the sweep. We recommend to check the vibration pressure during the sweep, if the pressure drops when distortion appears it is the root of the problem. So why the pressure could drop ? If the ground is bad : low cut off frequency, we have to check the phase base plate and top plate. If the vibration pump is bad : not able to supply enough flow because of intern leakage inside this one. If the mass is bad : segment are worn and you have internal leakage between HP and LP side. Servovalve and torque motor : seals are worn.
A good exercices to know if it is intern leakage is to do a sweep when oil is cold and when oil is hot, if distortion increases with the temperature it is typically problem of intern leakage. However in Middle East countries, the winter it is difficult to have oil lower than 30 degress to do the test it is good to have oil at 20 degress. Also we could look the overload it could give you indication to find find faulty components, such as

Overpressure
Overforce
Overexcitation
Overmass

We check hold down pressure. We check vibration pressure. We check nitrogen pressure.

The mass warning and base plate warning, should be prohibited : that means there is problem with cable, BOB or accelerometer itself. This problem is confirmed by segd file where the pahse between mass AS and base plate AS is clearly not normal and it is not link to ground cut of frequency. we could recommand to solve this problem and to check carefully the result of installation (mass, valve, torque offset are in specifications or not. THE LDVT from the mass and the LVDT from the valve should be in good conditions and if any of the above are not set properly and in good working conditions, your seismic data can be severely affected by high harmonic distortion and source generated noise.

HARDWIRE SIMILARITY ANALYSIS
CONTACT US FOR A FREE SAMPLE OF THE SERVICES- WE CAN ANALYZE ONE SINGLE 24 HOURS SEISMIC DATASET FOR FREE

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