Estimation of the Bubble Influence on the Imbibed Liquid Measurement During Tight Rock Continuous Imbibition

摘要

Bubble influence makes the measured liquid content in rock become less during continuous imbibition because it attaches to the surface of the tight sand increasing the buoyancy of rock in liquid. The imbibition experiment was performed to research this influence. The experiment has two parts. One is the repeated measurement of imbibition with the same sample to investigate the repeatability of the imbibition experiment under the bubble influence. The other part includes the measurement with bubble influence and without bubble influence of the same sample. The results are listed as follows. The repeated measurement of the same rock imbibition reflects a similar characteristic with the bubble influence. The water content is very close with the corresponding imbibition time. This characteristic presents that tight sand imbibition has the characteristic of repeatability, which was the basis for the other experiment. Some different characteristics appear during the measurement of the liquid content with and without bubble influence in the same sample. The liquid content without bubble influence is apparently larger than the liquid content with bubble influence. The difference between the liquid content in these two conditions is small at the end of imbibition time. It becomes larger in the middle imbibition time. The error can reach 50%. It severely influences the accurate evaluation of the imbibition capacity of tight sand. Our research contributes to the acquaintance of liquid imbibition in the formation during hydraulic fracturing and is also conducive to better measure the liquid content through the laboratory experiment.