Synthesis and Evaluation of a New Swelling Deferrable Lost Circulation Material

Gel lost circulation material (LCM) presently in use swells fast when absorbing water, making it difficult for the LCM to enter into the flow channel in formation through which mud is lost. Part of the LCM entering the flow channel forms plugs of low strength in the flow channels because of early swelling, resulting in poor mud loss control. A swelling deferrable lost circulation material (LCM), BZYD-1, has been synthesized with acryl acid (AA), methyl acrylate (MA), 2-acrylamide-2-methyl propane sulfonic acid derivative (AMPSA), and N,N'-methylene-bis-acrylamide (MBA), and characterized. Laboratory evaluation showed that BZYD-1 had good thermal stability, and was resistant to high temperature to 150℃. At room temperature, BZYD-1 did not swell in fresh water, and rate of swelling after soaking for 4 hours in alkaline water was less than 50%. At 80℃, BZYD-1 soaked in alkaline water swelled to 17.8 times of its original size, demonstrating remarkable deferred swelling. The swollen BZYD-1 had pressure bearing capacity of 4 MPa. This swelling deferrable LCM has good application prospect.