Atmospheric electricity, geological heterogeneity and - - PowerPoint PPT Presentation

Atmospheric electricity, geological heterogeneity and hydrogeological processes

Vladimir Shuleikin Oil and gas research institute, Russian academy of sciences 3 Gubkina street 119333, Moscow, Russia shvn1947@yandex.ru

The subvertical flow of hydrogen and methane captures radon from a depth

• f 4-6 meters and carries it to the near-surface layers of the soil and the

atmosphere. The light ions produced in the ionization process determine the polar conductivities of the air - PC; their recombination with neutral condensation nuclei sets the atmospheric electric field - AEF.

• 1. When measuring the volume activity of radon in the soil and

atmosphere, the RGA-01 sensor was used. The error in the determination of the volumetric activity of radon in each sample after the averaging is reduced to 17%.

Measuring equipment

• 2. The atmospheric electric field was registered with «Pole-2» and

«Gradient» field mills. The instruments provide the long continuous

• peration, have two automatically switch able measurement

subranges (±500 V/m and ±5000 V/m) with the relative error of 5%.

• 3. Polar air conductivities were measured using an aspirating

condenser unit. The relative measurement error is ~ 10%.

The registered variations in the field were the effects of dew evaporation as a result of solar heating, namely, of the injection of neutral condensation nuclei to the surface atmosphere that caused the dramatic increase in AEF

90 91 92 80 100 120 140 160 10:19 10:33 10:48 11:02 11:16 AEF, E1(z), V/m AEF, E(z), V/m Time, h., min. E(z) E1(z)

Above the zone of the ore body, a decay of the atmospheric electric field was registered on the order of 100 V/m The reason for the observed decline AEF - hydrogen formed at the top of the ore-body at the expense of electrochemical processes.

An increase in the density of the deep subvertical flux of volatile gases, including hydrogen and methane

Increased radon exhalation over the zone of a sharp lowering of the basement roof - a sharp increase in the thickness of sedimentary rocks ~ 3 km(data from the geophysical expedition of Belarus). Reversible electrode effect Increased radon exhalation over fault zones:

• the fault zone of the Aktash

river E(Ak)(Dagestan);

• the Kaluga ring structure E(Krs).

Reversible electrode effect.

• 0,7

0,7 1,4 2,1 3 6 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PC, l2, l+, relative units PC, l1, relative units. Picket numbers l1 l2 l+

Variations in the polar conductivities of air during observations:

• on the profile in the "cross" with a line of subway metro - l1, metro

Kon'kovo, observation step 4 m;

• on the profile in the "cross" with a deep underground line - l2,

Metro University, observation step 12m;

• on the horseshoe profile, twice crossing the karst cavity - l+ (Tula,

Soyuzny lane), the observation step is 4-12 m.

The increased exhalation of radon - the growth of polar air conductivities

• ver the regions of

decompaction of the earth's crust

2,1 2,4 2,7 3 3,3 3,6 3,9 4,2 50 100 150 200 250 300 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 Volumetric activity of radon, Bq / l АEF, V/m Picket numbers, step 100m Е E(Rn) Rn

A small subvertical flow of methane is present in plumes of oil deposits. At the 3rd Rechitsa oilfield at the new production well in 1989 and 1992, profile AEF observations were made twice: E (1989) and E (1992) Simultaneously with observations of AEF - E, the volumetric activity of ground radon, Rn, was recorded at

• bservational pickets. Linear

approximations of AEF were constructed, as functions of volumetric soil radon activity - E(Rn).

Variations of AEF - E(1989), E(1993) near the well on the 3rd Rechitsa oilfield . Variations of AEF - E, E(Rn) and volume activity of ground radon - Rn on the Aleksandrovskaya oil deposit (Belarus).

Decay of AEF as a result of a sharp increase in the pressure of seismoacoustic noise in the ranges 1.5-6.0 kHz and 6.0-10.0 kHz. Decay of AEF (increase in radon exhalation) is mainly influenced by acoustic noises of the range 6.0 – 10.0 kHz. Minimal AEF values take place about 30 minutes after the beginning

• f acoustic noise growth; approximately at the middle of the lifetime
• f heavy ions.

220 320 420 520 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 AEF, V/m Time, min.

Background at the r./way E from the r./way with a turn E from turn to r./way Background at the r./way

• 1,5
• 1
• 0,5

0,5 1 1,5 2 13:35 13:37 13:40 13:43 13:46 13:49 13:52 13:55 Polar cnductivity, *10-14Оm-1m-1 Time, h. min. l+ l- l

Relatively low AEF values for the railway and its subsequent growth when moving along the profile by ~ 200 V/m are determined by the high level of technogenic seismic noise (5-25 Hz) generated by the movement of the rolling stock. Temporal variations of positive, negative and total PP over the metro

• line. Intervals 13h35m - 13h39m and 13h50m-13h54m - record zero level of

the PP; 13h41m, 13h45m and 13h49m- the passage of the metro trains under the observation picket. Due to the growth of seismic noise during the passage of trains, there is an almost twofold increase in signal levels.

300 600 900 1 4 7 10 13 16 19 22 25 28 AEF, V/m Pickets, step ~ 600 m

Е1, morning Е2, noon Е3, evening

• 150
• 100
• 50

50 100 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 АEF, V/m Time, min Е1, background Е1, downloading Е2, background Е2, downloading

Variations of the atmospheric electric field during 1 and 2 cycles of pumping 30 m3 of fluid into the ground to a depth of 50 m. A sharp drop in the signal with a change in the sign of the field ~ [(-140) - (-50)] V/m somewhere in the 20th minute from the start

• f injection. The reason for this - a powerful

local release of the ionizer at the time of formation of hydraulic fracturing - the reverse of the classical electrode effect (See AEP with increasing seismoacoustic noise). Spatial variations of the AEF on the Svetlogorsk-Uznozh highway over the urban water intake zone. Peak values of the field

• n the traverse of the intake station ~ 400,

900 and 600 V/m. The reason for this is the depression funnel formed in the reservoir during the water intake

Variation of the atmospheric electric field above the sampling/injection zones of the fluid

Conclusion:

• growth of gas permeability of rocks in the zone of heterogeneity: fault zones,

increase in the thickness of sedimentary rocks, decompaction of the earth's crust (underground engineering structures, karstic cavities), leading to growth

• f PC and AEF decline;
• presence of a small subvertical flow of hydrogen or methane over the

geological heterogeneity: iron ore deposit, oil deposit, underground gas storage, cause AEF decline;

• natural gas deposits possessing high-tight tires, on the contrary lead to a

decrease in the density of subvertical flows of hydrogen and methane, which is accompanied by the growth of AEF;

• seismic noise of natural and man-made nature stimulates air-soil-atmosphere

air exchange - growth of PC and AEF decline. The effectiveness of the impact will increase with the fall of the oscillation frequency, and reach a maximum under deformations;

• an increase in groundwater level will lead to an increase in soil radon

exhalation - growth in PC and AEF decline; the decline in the levels to the reverse process - to the decline in PC and the growth of AEF. Executed assessments and materials of field observations clearly illustrate the possibility of using elements of surface atmospheric electricity for solving applied geophysical problems.

Thank you for attention