SU857893A1 - Method of seismic wave excitation - Google Patents

Description

(54) METHOD OF EXCITING SEISMIC WAVES

I

The invention relates to land seismic exploration, in particular to methods based on the explosion of an explosive charge in a well.

A known method of seismic wave excitation, in which a load with a charge attached to the bottom is lowered into a pipe placed in a well. The load serves as an inert mass that directs the energy of the explosion downward 1.

Closest to the proposed technical essence is a method of exciting seismic waves, in which the explosive charge is placed in a hardening mass poured into the well and initiate it after the solidification of the mass 2.

However, a medium with high acoustic rigidity P (where is the density of the medium, c is the speed of propagation of waves in the medium) is necessary to increase the spectrum of the excited frequencies. The hardening mass does not always have high P values. In addition, if there are cavities in the well, cracks, water with sludge, the density of the hardening mass and its uniformity are significantly reduced, which leads to a deterioration of the conditions for the excitation of high-frequency seismic components.

mical signal. The occurrence of cracks in the hardening mass leads to the exit to the surface of the combustion products of explosives, which, in turn, leads to the formation of additional interference in seismic recordings. Moreover, as the depth of blastholes decreases, in order to increase the fraction of useful energy going down, it is necessary to increase the explosive charge values. At the same time, the spectrum of the excited frequencies decreases, the risk of breaking or ejection of a column with hardening mass increases, which significantly limits the possibility of reducing the depth of blast holes.

The purpose of the invention is to expand the spectrum of the excited frequencies of seismic waves and reduce the depth of blast holes during fj seismic exploration.

Claims (2)

To achieve this goal, explosive charge will be pushed into a hardening solution poured into the wellbore based on a binder, such as cement, into which metallic particles uniformly distributed throughout the volume are added, for example, in the form of chips or sawdust, and after the solution is solidified, charge is initiated. The impurity concentration of the metallic particles in the hardening mass is selected depending on the state of the blast hole, its depth, the charge value and the required degree of mass strengthening. The method is carried out as follows. In the drilled well or schapur pour pre-cooked quick-hardening solution, in which the metal particles are evenly distributed. The volume of the mass poured into the well is calculated based on the magnitude of the charge, the diameter of the well, but it is not poured up to the wellhead in order to preserve the topsoil, since such works can be carried out in places suitable for thickening, i.e. Environmental conditions must be met. Charging is pushed into the well with an uncoupled pole. After the mass solidifies, a strong reinforced concrete plug is obtained and the charge is initiated. The proposed method of seismic wave excitation allows to increase the geological efficiency of seismic exploration and reduce the cost of exploration work at the expense of; expanding the spectrum of excited frequencies, since the explosion takes place in an environment that has a higher value of acoustic rigidity P (due to the presence of metallic inclusions in the solidifying mass). the proportion of energy in the high-frequency region of the spectrum increases, which leads to an increase in the resolution of the seismic survey; reduce the depth of the blast hole. This is possible in view of the fact that the quality of the closure is improved and there is no need to create a closure column of greater height. The amount of drilling operations is reduced, which reduces costs and speeds up seismic operations. The cost of metal shavings or Neve / 1ika sawdust, as they are taken from industrial waste; reducing the weight of the charge. A well closure allows to increase the excitation efficiency, i.e., most of the energy is directed downwards and creates useful waves, which makes it possible to receive sufficiently strong reflected waves from the studied geological boundaries with lower charge weights or deep intelligence. These advantages of the proposed method of excitation are confirmed experimentally. The conducted field studies show that using this method of excitation, a more resolution recording was obtained (the spectrum of recording frequencies is higher), the synphasic axis is clearer, the recording is more regular. With smaller depths of excitation and smaller weights of charges, it was possible to obtain a record of useful waves up to 5–6 s with clear axes of phase synchronization. Before applying this excitation method, in this area of work, it was necessary to drill several times deeper wells and to apply charge values much larger. Claims The method of exciting seismic waves by placing a charge in a solidified mass poured into a well and initiating it after it solidifies, which is different, in order to expand the spectrum of excited frequencies and reduce the depth of explosive wells, evenly distributed over the volume metal particles, for example. in the form of shavings or sawdust. Sources of information taken into account in the examination 1. US patent number 2507230, cl. 255-1.8, 1950. 2. The patent of France No. 2079648, cl. G 01 V 1/00, 1971.