Hole plugging technology with high-temperature resistance and wellbore strengthening capacity applied in the Xuwen X3 well

The Xuwen X3 well is one of the major exploratory wells located at the Beibuwan Basin by the Sinopec. The lower Weizhou Fm with developed pores and fractures has a poor pressure bearing capacity, resulting in severe lost circulations and lost-circulation material failures with a high BHT even up to 180°C. The conventional bridge plugging and cement plugging methods do not produce desired results, so it is necessary to develop the hole plugging technology with high-temperature resistance and wellbore strengthening capacity. First, the high-temperature resistant bridging material GQJ and the fiber material SW are optimized in experimental tests, then different particle sizes of calcium carbonate and mica are added as packing flakes according to the particle size distribution theory SAN-2, and finally the high filtration loss agent HH-1 and calcium oxide are also supplemented, as a result, the formula of a plugging fluid with high-temperature resistance is worked out. The evaluation experiments show that this formulated fluid can strengthen the wellbore to withstand pressures up to 12 MPa when plugging artificial fractures are 0.5 - 4 mm wide. This fluid is pumped for plugging downhole in stages, and the withstanding pressure of wellbore is increased to 4.5 MPa under conditions of complex formation. And there have been no such accidents as lost circulation in the Xuwen X3 well since the 3rd spud-in and the cementing job afterwards. So this developed plugging program is proved to meet the need of successful cementing in this well with good results obtained.