Dissolvable Ball as a Temporary Fluid Loss Control Device for Multilateral Wells

Commercially available fluid loss control devices (FLCDs) require intervention or the application of pressure to reopen the well for flowback and production. In some multilateral applications, well architecture may not allow re-entry to the laterals for mechanical intervention and/or the lateral junction (for TAML ≤ 4) might not be pressure isolated to allow pressuring down the lateral. This paper discusses the use of dissolvable balls to act as a temporary FLCD and thus, eliminate the need for an intervention operation or pressuring up the junction to open it. Additionally, an overview of lab tests and field trials performed will be discussed. Different dissolvable ball materials were tested. The test was designed to mimic the target well conditions using the target well's completion fluid, pressure and temperature. The ball that was best suited for the application was then selected for the field trial. A dedicated baffle was run as part of the lower completion inside the lateral, a few casing joints above the shallowest frac sleeve. After completion of all stimulation stages, the dissolvable ball was dropped from surface and pumped to the seat on the dedicated baffle mitigating fluid losses. No losses were observed while pulling the frac string and the multilateral (MLT) deflector out of hole, nor during upper completion installation. The dissolvable ball also did not affect the production flow during flowback operations. This was accomplished without intervention or the application of pressure through the TAML level 4 junction. Dissolvable balls can be successfully and safely used as a FLCD in lateral branches of MLT wells. This was proven through lab testing and field trial. The main advantage of this method over commercially available FLCDs is eliminating the need for intervention or wellbore pressurization. Furthermore, this method simplifies the operation, reduces risks and provides time and cost savings. Meticulous planning and testing are key for achieving success for such applications having strict time constraints to safely proceed with the remaining operations in the completions program. In the discussed case study, the ball provided up to 17 days of safe operations without losses as the upper completions was set and tubing hanger landed. Furthermore, during flow back operations of the lateral branch, which started 18 days after setting the upper completion (35 days after ball launching), no traces of the ball were observed. This paper describes the novel use of dissolvable balls as FLCD where traditional FLCDs are not adequate. Additionally, dissolvable balls offer simplicity as well as time and cost savings over other traditional fluid loss control devices. (El-Mallawany et al., 2022)