The Evaluation Method Research Of Fluids In Core Based On Two-dimensional NMR Technology

Measurement based on nuclear magnetic resonance can be received much less affection compared with the conventional logging technology, then the reservoir parameters calculated by NMR logging data is usually more accurate. The reservoir parameters processed by NMR logging data may served as the reference in the work of interpretation and evaluation under the condition of lack of core data. According to the transverse relaxation of pore fluids is different in routine, one-dimensional NMR logging technology can able to predict those aspects as various types of pore ratio of the underground reservoir, permeability parameter,and the existence both of oil and gas through inversed relaxation spectrum. The logging data,however, measured by one-dimensional NMR always contain the low SNR for the problem of measurement technology, and moreover the relaxation single of fluids in core usually has more overlap range in order that the interpretation is not accurate enough derived from the methods such as differential spectrum and shifted spectrum.The proposal method of two-dimensional NMR technology has solve the problems above well in interpretation and evaluation of fluids in reservoirs. Nonetheless the current inversion methods of two-dimensional NMR are not skillful enough in the calculation speed and accuracy of results. In this view, the new method is designed to study on the base of the TSVD method which includes in the classic subspace inversion methods. With the deep research both of the truncated singular value algorithm structure and that of the iteration algorithm that contained in the TSVD method, the truncation and packet processing algorithm of singular value is proposed in a creative way, as well as the variable parameter iteration algorithm. The new method is detected in two parts: the numerical simulation and the core experiment. In the numerical simulation, the different dimensional structured spectrum can be quickly and efficiently restored by the new method, the distribution and peak value of the fluid single inversed by new method are largely fit with that of the structured spectrum,which can reflect the fact that the inversed result is reliable. In the core experiment, new method can able to calculate the accurate saturation and the relative error is controlled under the 5 percent. Test results show that the new method is not only fairly correct in theory, but has the capacity to tackle with the practical core data derived from the two-dimensional method and obtain more accurate interpretation and evaluation of fluids in core, which manifests the truth that the new method not only embodies the practical application value, but also provide the idea of researching other inversion methods of two-dimensional nuclearmagnetic resonance.