An experimental procedure is proposed for the occurrence state of reservoir fluids in microscale pores of tight reservoirs.
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The recoverability of reservoir fluids in microscale pores is experimentally discussed.
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For the first time, the oil film in microscale pores is divided into immobile and movable states by a centrifugal method.
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This study provides a fine calculation method on the recoverable oil reserve in tight reservoirs.
Abstract
Occurrence state of fluids in the microscale pores of tight reservoirs significantly affects the flow behavior and recoverability of reservoir fluid. Currently, microfluidic technique and CT (Computed Tomography) scanning have been widely applied on the reservoir pore structure evaluation and fluid flow behavior characterization due to their high resolution. In this study, combining a microfluidic chip test and a micro CT scanning test on tight rocks, the occurrence state of fluids in microscale pores is experimentally investigated. A set of tests on the microfluidic chips are performed to change the environment temperature, pore size and fluid compositions. Then, combining the results of micro CT scanning on real tight rocks and the results of microfluidic chips, the immobile and movable oil films in microscale pores can be obtained. Results indicates that the oil film thickness in microscale pores is negatively correlated with temperature and positively correlated with pore size. The effect of pore size can be neglected when it is above 15 μm. The higher the molar weight of fluids is, the thicker the oil film is. And the proportion of immobile and movable states are also closely related to the fluid compositions.
