Research On Application Of Borehole-to-ground Resistivity Tomography Method

Method of tomography of borehole-to-ground resistivity is one of electromagnetic exploration methods, which comprehended electric logging method and resistivity method. Concise introduction of this method can be showing from the following sentence. Putting one power source in some depth in well and then surveying every pole potential on the surface is the method principle. Through this method, the characters of stratums among boreholes would be directly responded. The technology of tomography of borehole-to-ground resistivity has its own vantages if compared with other exploration methods. One of the most important parts in this dissertation contains designing of numerical model that is viable for researching on the anomalous body exists in underground. Through founding enough numerical models and finding optimal method, besides, the following content plays important role on the total dissertation.First, according to finite-difference method and anomalous potential Laplace equation, the forward models with several variations were designed, contained homogenous medium model, high resistivity block model, low resistivity block model, horizontal layer medium model, vertical layer medium model. Relying on these forward models, surface potential used for inversing medium resistivity was simulated, and following the increase of depth, the value of surface potential decreased obviously. Second, using the surface potential from forward model to inverse the anomalous body by method of continuation of potential field and smooth constraint minimal constructor, the resistivity slice about exact depth in rang of anomalous body burial depth could be achieved, which the forward models needed to compare with. The results of contrast among them verified in horizontal and vertical direction the inversion method had desirable consequent, besides, in depth direction the resolution was also ideal. Finally, to consider the numerical imitation should be applied in the engineering, this method the dissertation research on was used in some waterflooding oilfield, and gained resistivity slice by the dissertation method. In order to testify the result veracity, by virtue of diagram of degree of oil saturation the contrast about anomalous district between resistivity slice and saturation was anastomotic. The method can be available for the waterflooding oilfield.Therefore, through simulating different models with the forward method and applying in the engineering with inversion method, the forward method and inversion method in this dissertation has practical significance and can be learned. Especially, in the waterflooding oilfield, one system of interpretation of detecting oil and water is set up, which can be available for distinguishing the interface of oil and water by different characters of oil and water. Consequently, it can service for enhancing oil recovery in waterflooding oilfield. By means of serving for enhancing oil recovery with this method, which can be opted to apply in other field of technical engineering, such as solid mineral resources exploration fields, safety field of monitoring mineral mining, monitoring and evaluation of environmental pollution in groundwater fields, environmental resources monitoring fields, hydrogeology survey fields, engineering prospecting areas, archeological fields and municipal engineering, etc, so in order to satisfy the needs of different engineering field, this method provides a new way to achieve significant influence.