The Method Of Research On Electromagnetic Exploration While Drilling

Method electromagnetic exploration while drilling refers to supply the current into the exploitation well and observe the electromagnetic field on the ground. It is mainly used for the prediction and delineation of favorable areas of oil and gas reservoir boundary. In general, we provide a high-power current into the underground through the development of cased well and measure the potential distribution on the ground. This method by analyze the relationship between the electric field distribution and the oil and gas reservoirs, divide the abnormal of electrical interface and the prediction of hydrocarbon layer extension of the law and azimuth. It found the method that can be used to dope out residual hydrocarbon and water boundary by researching the influence caused by the change of oil-water model.Compared with other well logging method and ground electromagnetic method, Electromagnetic Exploration while Drilling which probing depth is greater, the ability to probe more deeply target body is more powerful. It has the advantage of fast speed, low cost, good generality, do not destroy the environment, can be used for marine etc. It has the good effects that other exploration methods can not achieve. Electromagnetic Exploration while Drilling method can be better adapted to Chinese large-scale survey of mine, large-scale to find water in arid regions, and the increasingly serious problem of resources. Therefore, it is necessary to study of vertical long wire source in layered earth.This paper based on the current formula, and principle of using the finite difference method to simulate the forward problem of the vertical line source electromagnetic exploration while drilling method. First we introduce the basic theoretical knowledge about electromagnetic exploration while drilling method, the derivation of the basic formula and boundary conditions are given. The second is to introduce the field with the drilling electromagnetic wells to DC line source signal transmitting and receiving, including the introduction of some of the general use of the method of choice of the electromagnetic method instrument and field specific construction methods. Thirdly Casing down-hole reservoir according to the actual situation of the oil, gas and water distribution, while drilling electromagnetic well ground source underground model, established a two-dimensional geo-electric model the actual situation of the oil field, the establishment of differential equations, finite difference method programming calculation of the ground model. Fourth, has been given several underground resistivity distribution into the written procedures, inspection procedures, as well as the applicability and accuracy of the model.At present, this method has been used in eastern and western China’s oilfields. Among them, the charging method for monitoring oil and gas field water injection fracturing more commonly, due to the casing supply inflow of the target formation current casing evenly distributed, coupled with generally measure only the component of the ground potential, the existing methods is also difficult to effectively distinguish the different shades abnormal source, but for oil field water monitoring to determine the water precursor to the orientation. This article underground DC line source excitation, the observation ground potential. The simulation studies have shown that the oil and gas reservoir under the DC line source excitation, the ground potential is extremely obvious, better delineation of hydrocarbon reservoirs boundaries. DC line source excitation there are still not high resolution, it is difficult to effectively distinguish between multi-layer reservoir, as well as anti-interference ability is poor inadequate.Respectively uniform subsurface model, underground medium low resistance cuboid model into the program calculate the verification in the high impedance of the rectangular model and underground media, which have significant potential abnormalities in the presence of high and low resistance body media, and the shape and assumptions the model is similar to prove that the method can monitor the remaining oil and gas distribution or injection leading edge position on oil exploration.