The Research On Shooting Condition Of Seismic Exploration In The Complex Area

Seismic exploration area is becoming more and more complex, showing inincreasingly complex topography and underground geological structures. In recent years,with the oil and gas exploration degree rising constantly, the focus of Jilin exploration areagradually turns to complex area exploration.Refraction determining high layer thickness and single well depth design using in theprevious field exploration acquisition cannot satisfy the requirements of the high precisionexploration any longer. This paper studies the effective and practical technology of seismicdata acquisition in complex exploration areas, from following aspects including finesurface survey technology, well depth design technology, explosive quantity research,combination well stimulation research and so on.Jilin exploration area with large surface fluctuatio, Multi-strata, more complexsurface type and fast lithology change, particularly in relation to the sand hill, rivers,gullies areas, in the vertical and horizontal, velocity and thickness of Low-velocity layerchange quickly. Complex surface type and near-surface structure caused difficulties to thefield construction, layout and method design of the surface survey point has greatdifficulty. Only by use of reasonable surface survey method, can we accurately implementthe surface structure。Near surface investigation can be more precise in low subweatheredzone by micro-logging.. Apply professional Micro-logging cable to construction process,and the collected data were interpreted by KLseis software. lithology logging duringdrilling, as well as distribution and scope of different lithology in different regions shouldbe investigated.In seismic exploration, shooting depth directly affects the wavelets get the highestenergy or not, the received shooting wavelets is more complex in composition, which isthe original and secondary downgoing wave superposed on each other to generate a composite wavelets, in different depth, superposition of upgoing wave and downgoingwave is at the different time, which results in the interference result is not the same, wegreat need to analyze and understand the effect of virtual-reflection on amplitude andfrequency of shooting wavelets. By frequency characteristics analysis and amplitudecharacteristics analysis field test comparing,it can be determined: During deep seismicexploration, select below virtual reflecting interface quarter depth of the wavelength as theshooting depth, which can make the shooting wavelet to obtain the strong energy, so as toimprove deep energy. So we can ascertain the well depth by the quantitative analysis ofthe shooting wavelet detecting and virtual-reflection investigating.In the previous deep seismic exploration of Jilin exploration area, requires anincrease in the maximum energy and also requires to improve the resolution of deep data,so it is essential to carry out comparative analysis on explosion properties of the explosivetesting and comparison of dose size test. In general, we called the below2kg quantitysmall doses in Jilin exploration area. Through the test contrast analysis: the small dose canmake high frequency, In special areas we use2kg small doses can meet the requirementsof data quality and ensure the safety conditions; With the increase of the dose, amplitudevalue increases in the whole frequency band and the peak frequency decreases, but at thelow frequency which less than peak frequency, with increasing of dosage,the increasedamplitude of frequency components is larger than high frequency; Large dosage canpromote deep reflection energy, deep seismic exploration will be better effect with theadoption of large dosage. In addition, improving the coupling between explosives and thesurrounding medium is also one of the means to improve data quality.Combination well stimulation is frequently used method of shooting in deep seismicexploration. As a very critical motivating factor, choose the appropriate combination ofwells spacing is very important. Through different combinations of base from thecomparative analysis, increasing pattern length is conducive to improving the quality ofdata. In Jilin exploration area, the combination well of2-3well with10m wells spacingCan improve the signal-to-noise ratioReceiving part, according to the characteristics of different regions, different interference waves, use different methods to suppress interference waves. Based on pastexperience and the suppression of interference waves combination theory, carry out anresearch on combined suppression of interference waves. In some of the more complexwork area, the interference wave is random without direction, this time with four series ofgeophone area combination to suppress the interference wave in each direction oftransmission...