References: <009801cd8141$def30be0$0501a8c0@xphd97xgq27nyf> <1345747032.3527.17.camel@gerhard-desktop>
In-Reply-To: <1345747032.3527.17.camel@gerhard-desktop>
Mime-Version: 1.0 (1.0)
Message-Id: <40000788-DB4D-4EA3-BD0E-72DB5DF07CBB@dk8kw.de>
Cc: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
From: Holger 'Geri' DK8KW DI2BO W1KW <geri@dk8kw.de>
Date: Thu, 23 Aug 2012 22:44:09 +0200
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=us-ascii
Subject: Re: LF: gas es oil cales
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Mal and all,

By profession I am probably one of the competent people to reply, I am a Pet=
roleum and Drilling Engineer working in the service sector of the oil and ga=
s industry.

Regarding the cables I can confirm what Gerhard mentions in his mail below, t=
hese geophones pick up reflections from artificially created noise, mostly f=
rom explosions or also from vibrating trucks on the surface.

There is, however, the use of VLF in drilling operations. There is a sort of=
 Measurement While Drilling technology, which uses low frequency currents to=
 transmit data from the drill bit some several thousand meters below the sur=
face to the surface. those systems are called EM-MWD, which means electro-ma=
gnetic, however, is is more an AC modulated DC current that is used to ident=
ify and demodulate the data. Frequencies here are in the hundreds of Hertz r=
ange, and, hence, should not be any trouble to our VLF/LF/MF activities.

Also, there are systems used for what we call borehole logging, which are se=
nsors that are used in boreholes to determine the formation properties, that=
 use frequencies of several hundred kHz, equal to LF or MF. Those are, howev=
er, injected into the formation way below the surface and we might only be a=
ble to detect those if a drilling rig is very close to our homes (not comple=
tely unlikely because several geothermal drilling activities are carried out=
 directly in cities and populate areas these days). I know, however, from te=
sts we (my company) carried out back in the 80ties, that those signals are a=
ttenuated some 200 db (!) on their way from the borehole bottom to the surfa=
ce.

Vy 73

Geri, DK8KW & DI2BO

P.S.: Gerhard, where do you live? I assume the seismic activities near your h=
ome are carried out for OMV? It's one of my clients and I am in Vienna aroun=
d twice a month.


On 23.08.2012, at 20:37, Gerhard Hickl <gerhard.hickl@aon.at> wrote:

> Hi Mal!
>=20
> I live in an area (very Eastern part of Austria) which has GAS/OIL
> resources. During the past two decades, it was common here to search for
> new sources with the method you described.
>=20
> As far as I know, those cables aren't carrying any kind of signal, but
> rather they are used to transfer signals detected by probes
> (microphones) to a central data-processing station.
>=20
> The sources of this "noise" detected by the probes could be either
> explosive loads, detonated in drilled holes up to some hundreds of
> meters in depth, or vibrations generated by special machines. Those
> machines are kind of Caterpillars with a big vibrating metal plate at
> the bottom which is transferring mechanical vibrations into the ground.
>=20
> =46rom the radiation patterns, picked up by the many probes (microphones)
> which are connected via a mesh of cables, geologists can tell about the
> position of a undiscovered potential Oil/Gas - field.
>=20
> So as far as I know and have experienced, there is no threat to our
> activities.
>=20
> 73
> OE3GHB
> Gerhard
>=20
>=20
>=20
>=20
> Am Donnerstag, den 23.08.2012, 15:13 +0000 schrieb mal hamilton:
>> LF/MF
>> Seemingly some cables are being layed through out some parts of the UK
>> for GAS es  OIL exploration. These cables will will carry a signal to
>> penetrate the earth and detect if gas/oil is below. There will also be
>> some small explosive charges at times in the earth and these will be
>> detected also by the cable and fed to a master station.
>> Does anyone know what frequency is transmitted down these cables or
>> mode of transmission PULSE etc
>> This could be a source of QRM for the LF/MF radio amateur and most
>> people do not know it is taking place and wondering where the QRM is
>> coming from.
>> There will be a network of cables for hundreds of miles lying on
>> fields and ditches etc while the exploration is going on
>>=20
>>=20
>> de mal/g3kev
>>=20
>=20
>=20
>=20