A Plugging Evaluation Device Design And The Working Liquid Performance Evaluation Research

Lost circulation is used to be a commonly and major problem in the drilling engineering. When lost circulation happens, it would trigger many accidents in the downhole such as well sticking, blowout, borehole collapse, which would increase the drilling time, waste lots of the drilling fluid and the leaking stoppage materials. What’s worse, we have to abandon the well when the loss circulation controls failed many times. It has been found that making indoor evaluation of plugging simulation to select a kind of plugging working fluid system before field engineering is an effective way to increase the plugging successful rate.In this paper, the methods of foreign evaluations is to put an orifice plate or fracture plate at the bottom of a HTHP static filter press to simulate the pores and fractures. And another method is to put marbles to simulate bray stone loss in a barrel or to simulate the plugging test on sieves of a filter press at a normal temperature. Many domestic oilfield units have developed their own featured evaluation equipments based on the equipments above. However, these equipments still have many places to improve. First, the preparation of plugging working fluid is not refer to evaluate process. Second, as the plugging working fluid is prepared at a room temperature that it can not figure out the real performance as the temperature and pressure increasing in the wellbore. Third, the curing process of the plugging working fluid is not available in the equipment. Fourth, the different pressures between the wellbore and the formation cann’t be precisely controlled. So these defects of the equipment make the indoor evaluation hard to instruct the field engineering.In this paper, a new plugging simulation equipment is designed basing on the earlier experimental demonstration of the simple simulating equipments. The general structure, driving system, wellbore simulation system, program controlling system, measuring system and some other assisting systems are designed in this new equipment. What’s more, it is produced under the help of production factory. After production, the performances of this equipment are tested as plugging, temperature and pressure controlling, so that the problems are not only found out but also well settled respectively. This equipment has also made a dynamic plugging simulation as formation temperature(0～200℃),formation pressure (0-120MPa),pressure differences(0-40MPa)and different leaking aisles directions(0～90°). The plugging fluid evaluation tests proved that all the aspects of this equipment could be well performed so that it could meet the requests of designments.