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With the development of the global oil industry,the production of the normal or high permeability reservoirs decline rapidly. Therefore, more and more low permeability reservoirs are used to the production stimulation. The oilfields overseas make great contribution to CNPC. The HF oilfield is one oilfield that the CNPC have in overseas. The HF oilfield is mainly the low permeability carbonate reservoirs which make it not easy to economically exploit. Due to the reason that the low permeability carbonate reservoirs present small porosity and the fluid’s flow situation in the low permeability carbonate reservoirs, the flow doesn't obey the Darcy's law. Thus it is greatly necessary to study the non-Darcy percolation characteristics. In this paper, the HF ‘s low permeability is tested and the threshold pressure gradient test is finished ,according to the experiment results, the nonlinear percolation ‘s law ,which is suited to HF-oil field , is illustrated and the reservoir classification is achieved.

The permeability of tight oil reservoir is very low and general perm-plug method always has a big difference. The results can’t reach the test accuracy requirements. This paper measured 26 block rocks of Changqing tight oil reservoir and several typical tight oil reservoirs in CNPC with pulse decay new method. The result shows that the pulse decay permeability measured in the new method and steady-state Klinkenberg-corrected permeability have a good relationship. We drew a figure about the porosity and steady-state Klinkenberg-corrected permeability of these tight oil reservoirs. This research offers a technical support to the tight oil reservoirs about basic data permeability measurement.

Aimed at ultra-low permeability reservoir, the large natural outcrop model has been made for researching the oil reservoirs porous flow law deeply, and the inverted nine-spot equilateral well pattern also has been designed which is the commonest well patter during the oilfield exploitation. The flow fields have been measured during the experiment in different displacing period (0.3PV, 0.6PV and 1PV). The research shows that fluid flow has obvious directivity, and it strongly affected by heterogeneity of the reservoir. In addition, the regions between the edge production wells are much more difficult to be exploited.

Low permeability reservoir is one of the most important petroleum reserve types in China. Therefore, some basic scientific problems about low permeability reservoir such as pore-throat size distribution, principle of porous flow should be deeply studied. Pore-throat size distribution, based on 69 cores from Changqing and Daqing oilfield of China, has been measured by comprehensive using Constant-Rate Mercury Injection and Nuclear Magnetic Resonance. It has been found that the Nano-pore-throat takes more than 60 percent of the total pore-throat of the low permeability reservoir and it is the key factor affecting the flow capacity when the permeability is less than 0.5×10-3μm2. The nano-pore-throat takes less than 40 percent of the total pore-throat and micron-pore-throat takes more than 45 percent when the permeability is larger than 5×10-3μm2. And Micron-pore-throat is the key factor affecting the flow capacity of low permeability reservoir. But when the reservoir permeability is between 0.5×10-3μm2 and 5×10-3μm2, its flow capacity is determined by the sub-micron-pore-throat and the amount of micron-pore-throat. Additionally, the key forces in micro-, sub-micro- and nanoscale pore-throat has been got by analyzing. The electrokinetic coupling matrix of mass transport has been gotten by analyzing the characteristics of the mass transport in small tube at different Debye ratio and pore-throat size distribution of ultra-low permeability.

Chang 6 oil-layer in Huaqing district of Changqing oilfield is a typical thick oil layer with ultra-low permeability. After 2 years' water flooding development, some of the production wells have been flooded with low oil recovery. Based on the geological model of Huaqing district, the ideal numerical models are established using the nonlinear flow numerical simulation software. Then the characteristics of water flooding development and influence factors are researched. At last, the perforation degree is optimized. The numerical simulation results show that the best perforation degree for positive and inverted rhythm of thick oil layer is 0.2 and 0.4 respectively.