While drilling an exploratory Eaglebine/Buda play area of East Texas, an operator experienced major shale instability while attempting to use fresh water and polymer based mud systems. Smectite and similar swelling clays made oil-based drilling fluids the only viable solution. Unfortunately, fractured and porous formation characteristics meant the operator was experiencing significant losses on pilot wells (average OBM losses were 2,394 bbl/well) before employing the Prototype LCM Recovery System.
The operator initially utilized sweeps and then bypassed the rig shale shakers to help retain LCM, but the usual negative side effects occured:
High % of LGS & HGS alike
Drillsting and Standpipe washouts became more prevalent
Mud pump fluid end washouts and shortened expendables life
Pits filling with cuttings and significant mud losses from dumping the same
Downhole tool failures from improperly mixed LCM or slugs of material when pumping sweeps
To combat losses, we developed an LCM Recovery System Prototype unlike any other, designed to effectively “bypass” rig shale shakers and take full flow from the wellbore, while still returning high gravity solids and cuttings to the same shakers at a later point in time (after separation from drilling fluid and entrained LCM.)