Case History

Lab Work & Field Results Leads to Success with STAR SHIELD® 3000 in the Brown Dolomite

United States
Challenge

Wells drilled near Arnett, Oklahoma in Ellis County are known to have prolific drilling fluid losses in both the intermediate and production sections. While drilling the intermediate section through the Brown Dolomite, the operator consistently experienced lost circulation issues and would have to set intermediate casing near 6000-ft. When drilling the curve and horizontal section with OBM, the operator would experience seepage and total losses. The operator wanted to prevent lost circulation issues in both sections and eliminate the intermediate casing string, drilling from surface set, at 2000-ft, to total depth (TD) at 15,000-ft.

An operator requested Impact’s Technology Center perform comparative tests for two low weight drilling fluids (9.5 lb/gal WBM and 9.5 lb/gal OBM). The drilling fluids incorporated STAR SHIELD® 3000 and were tested on elongated slots alongside a conventional lost circulation material (LCM) to determine the most effective sealing product. These tests supported the use of STAR SHIELD 3000 in the circulating system.

 

Solution

The operator accepted the recommendation from Impact’s Technology Center to drill the intermediate interval (Brown Dolomite section) with a light weight WBM incorporating 6 lb/bbl STAR SHIELD 3000 and 6 lb/bbl conventional LCM.

The operator then drilled the production section with an OBM incorporating 5 lb/bbl STAR SHIELD and mixed a standby pill treated with 15 lb/bbl STAR SHIELD 3000 and 15 lb/bbl LCM to be used in sweeps if losses were experienced.

Results

The opeator drilled to the intermediate interval (Brown Dolomite) with fresh water and displaced the well with a WBM system incorporating 6 lb/bbl STAR SHIELD 3000 and 6 lb/bbl conventional LCM. The operator drilled to the intermediate TD at 6040-ft without losing drilling fluid. The opeator wireline logged, ran intermediate casing, and cemented without losses.

The operator displaced the cement with OBM and 5 lb/bbl STAR SHIELD® wellbore stabilizer. An 80-bbl pill was mixed with 15 lb/bbl STAR SHIELD 3000 and 15 lb/bbl LCM and stored to be used in sweeps if lost circulation was encountered.

When drilling and sliding at 7282-ft the operator encountered 10 bph seepage losses. The operator pumped a 30 lb/ bbl of the STAR SHIELD 3000 and LCM pill and losses ceased after it cleared the bit.

At 12,213-ft after tripping for a new lateral assembly after motor failure, the operator calculated a loss of 30 bbls during the trip and were experiencing seepage losses at 10 bph. The operator pumped another a 30 bbl STAR SHIELD 3000 and LCM pill which stopped the losses once it cleared the bit.

At 14,052-ft the operator encountered losses at 204 bph. It was decided to pump a 35 bbl STAR SHIELD 3000 and LCM pill and losses slowed to 140 bph. The operator pumped another 35 bbl STAR SHIELD 3000 and LCM pill and losses slowed to 10 bph. Once they were back in rotation, losses stopped altogether. The operator drilled to TD at 15,035-ft, ran 5.5” production casing with no issues, and cemented with full returns.