Three Dimension Reservior Electrical Resistance Tomography Technique For Residual Oil Exploration

Petroleum and natural gas occupy an extremely important position in the energy strategy of China. At present, China is experiencing a rapid increase in oil and gas consumption, and energy has become the largest "bottleneck" restricting the economic development of our country. To increase EOR (enhanced oil recovery), increase production of the developed oilfields and keep domestic crude oil production stable are urgent priorities for the three biggest oil companies and oilfields in China as well as important measures for the Chinese oil industry to start a new undertaking and achieve sustainable oil/gas development. According to the actual situation of oilfield development, 80% of China's crude oil reserves remain undeveloped and there is a considerable amount of subterranean remaining oil, although its major oilfields have entered a stage of high-water-cut development. By comparison between North America oilfields and Henan Shuanghe Oilfield, we have found that there is still much room for increasing EOR in China. A great deal of analysis and research illustrate that, the key to increase EOR, keep crude oil production stable with increases, decrease water cut in production wells i s to find out the distribution of subterranean remaining oil and to determine remaining oil saturation in reservoir beds and remaining reserves, which is an important foundation and prerequisite for effective application of stable production and tapping latent reserve measures and thrice oil extraction technology. The development of international geophysical inversion technology, especially the development and constant improvement of tomography for electric magnetic field of oil-gas reservoir, the opening up of domestic super computer system, the application of parallel calculation, the improvement of observation precision of electrical instruments and the attainment of multi-channel high-density data collection system have all provided effective geophysical means and economically feasible ways for the investigation and direct prospecting of subterranean remaining oil. After a great deal of work, we have finished theoretical and methodological research on three-dimensional resistivity tomography of reser voir beds, theoretical analysis and calculation of a mathematical model, computerized numerical simulation, computer programming for data processing and interpretation, and have carried out large-scale production test in Zhongyuan Oilfield and Changqing Oilfield, which have obtained positive results. By using 3-D resistivity tomography of reservoir beds and the correlation between oil saturation and resistivity, we can directly get to know the remaining oil saturation in reservoir beds and the spatial distribution of remaining reserves, so as to solve the unresolved international major issue: tapping oil reserve based on water flooding recovery methods, dynamic monitoring of oil-water distribution and remaining oil monitoring in high-water-cut stage.