震電勘探技術 精確瞄準地熱帶 彈無虛發

An seismic wave generated electrokinetic potential method and geophysical technology for directly locating groundwater aquifers to deduce the associated petroleum hydrocarbon reservoir structure with high accuracy, low cost, site access , portability, and simple operational procedures in the field.

The seismoelectric method is different from conventional seismic prospecting or an electrical resistivity survey, which separately register either a seismic impulse velocity or electrical resistivity sounding data in the geological structure. Seismoelectric make use of the different physical character between the ground-flow(water and oil) from the earth solid (rock or soil) to locate ground-flow directly.

DC-4500 Seismoelectric Ground-Flow Locator receives both a seismic signal and a seismoelectric signal generated by the same seismic source. The penetration of seismoelectric signal is depend on the power of seismic source. We have got 7000 feet depth reservoir seismoelectric data in LA with a Buffalo gun seismic source. We also have seismoelectric data from 30000 feet depth with a special testing.

DC-4500 Seismoelectric survey can avoid dry holes in water well drilling, indicates groundwater in real time analysis. With further data processing and interpretation with the reference application to locate such fluids- crude oil or natural gas.

Seismoelectric survey can also work with seismic survey. With the same seismic source, we can get both seismic data and seismoelectric data at same time give additional ground-flow information to the seismic survey, with lower cost. To indicate groundwater, seismoelectric signal is around 70% match the well log nearby.

Seismoelectric Survey Principle

Seismoelectric effect is associated with charge activities taking place at the mineral-water interface,defined as the electrical double layer (EDL). When a seismic wave passes through a porous rock, it agitates movements of both the rock frame and the pore fluid, not at the same rate. Relative movement between fluid and solid particles disturbs the electrical double layer, which in turn produces electric charge movement. Eventually the variation in electric charge creates an electric potential signal, which can be detected as a seismoelectric signal.

Seismoelectric (SE) survey method is a technology based on the seismoelectric effect. It measures the electric potential signal at ground surface with a seismic source for detecting subsurface water properties. This potential is a function of rock porosity, permeability, fluid contents and their saturation.

Superior to Seismic Reflection method, seismoelectric signals could be screened by proper arrangement of surface probes for vertical transmission. Hence it can reduce the influence of noise from diffraction and out of plane reflection commonly associate with seismic reflection method. Furthermore, since seismoelectric signals are related to fluid properties, the SE method could provide additional parameters for petrophysical properties.

SE signals are sensitive to the permeability of the rocks, therefore SE survey has served as a valueadding tool for the underground aquifer detection for the last five years by Seismo Electronics LLC. in many areas of the world. The principles of seismoelectric water value color strips (SEW) interpretation are shown in the figure below.

SE Surveying Method Vs. Other Traditional Surveying Methods

Seismoelectric (SE) survey method is a technology based on the seismoelectric effect. It measures the electric potential signal at ground surface with a seismic source for detecting subsurface hydrocarbon reservoir. This potential is a function of rock porosity, permeability, fluid contents and their saturation. The successful rate for SE survey in oil reservoir detection is higher than 50%. Seismoelectric (SE) survey can also work with seismic survey. To use the same seismic source, we can get both seismic data and seismoelectric data at same time. The seismoelectric signal work as pseduo-well log to be projected to the seismic section to give additional ground-flow information to the seismic survey, with lower cost.

Seismoelectric (SE) survey also can detect the hydrocarbon reservoir below the salt dome. In some area, the salt layers sometimes covered reservoir, and the seismic wave is difficult reflected back to the surface. Therefore, it is extremely difficulty for traditional seismic surveying method to detect the hydrocarbon reservoir below the salt. However, salt is a good conductor, hence seismoelectric signals can identify the potential hydrocarbon reservoir below the salt.

One set of survey equipment includes signal receivers, one data collector and seismic source. We use two geophones and four electrodes as signal receivers, one Seismoelectric Ground-Flow DC-4500 Locator as a SE data collector, and Buffalo Gun as seismic source. DC-4500 locators have total 4 channels. Channels 1 and 4 are used to connect with 2 geophones: one is placed 5 meters away and the other is 20 meters away. These two channels are in charge to receive the seismic signals. Channels 2 and 3, connecting with two pairs of electrodes spaced with one meter along a line, record the seismoelectric signals. When a seismic wave produced by a seismic source passes through a porous rock, it agitates movements of both the rock frame and the pore fluid, not at the same rate. Relative movement in turn generates an electric potential signal, which can be detected as a seismoelectric signal. After further data processing and interpretation, we can detect the depth location of the hydrocarbon reservoirs and estimate the r volume.

With some special requirements of our clients, we have also tested a weight drop seismic source methodology of generation in the seismoelectric survey. The tested data shown that one drop energy of A200 P/S Hammer is similar to a 2.5 inch 12 gauge cartridge acoustic impulse. However, the relative cost of this weight drop seismic source is much higher than using a buffalo gun.