Experimental Study On Ground Pressure Test Theory And Ground Simulation

Formation pressure test while drilling is test technology for formation pressure in the short downtime after drilling the formation.It is the international advanced technology because of the real-time and accuracy in obtaining the set of test parameters. It is of great significance to solve the problem of drilling safety, save drilling time and drilling cost. Because of the complexity of the underground environment, the technology faces many difficulties, in which the test data interpretation and the effective control of the test total time are two of the main difficulties.In order to solve the problems above, it carries out the following work.(1) Based on the seepage theory and considering the effect of formation heterogeneity, pipeline, super changing pressure, skin factor and other multiple factors, through deduction, it establishs a theoretical model of formation pressure test while drilling. Compared to the current model, this model is more comprehensive because considering more factors and can better reflects the test response process because the descriptors of the test response process is more detail.(2) Based on the theoretical model of formation pressure while drilling test, considering the performance of instruments (measuring precision, the maximum volume and pumping capability) and the range of total test time and other actual operation factors, through deviating, it forms a feasible theory to determinate test parameter. According to this theory, it can not only obtain permitted test parameter range (suction rate, the suction volume), ensuring the test reliability and the effectively control of the test time, also can obtain the theoretical corresponding sequence curve of the test.(3) Based on the test model and test parameter theory, it makes a compilation response analysis program, the procedure of explaining formation pressure and the testing parameters determining program, using VB platform.(4) Through the analysis of the test flow law in the downhole and boundary seepage law on the ground, it makes the theory of establishing test platform of simulating the formation pressure test while drilling, and deduces the relationship of the core length, core radius and the probe radius. Based on the theory, a ground simulation experiment platform is establishedusing the simulation platformt, it carrys out simulation experiments, Verificating the model of formation pressure test while drilling and the theory of test parameters.(5)Using the formed test theory of formation pressure test while drilling, it carries out the design of the core components (suction system), giving the controlling relationship between pipeline volume, probe radius, suction cavity volume, the pressure drop and test test time.Through the above research, it forms an effective theory of formation pressure test while drilling. It can well interpretate test data, obtaining high accuracy interpretative value of formation pressure, on the other hand, can be very good to determine test parameters, ensuring the test reliability and effective control of test time.