Target Drilling inc.

Plugging CBM Wells with Reformulated Polymer Gel and Target’s New Gel Unit

The bottom 1,000 feet of a CBM horizontal well’s (DD2) right lateral was successfully plugged with reformulated polymer gel using Target’s new gel mixing and pumping unit after following protocol established designing the reformulated gel specifically for DD2. The operational strategy included: 1) re-entering DD2’s right lateral to confirm it was open conducting confirmation surveys compared to surveys taken when drilled; 2) installing a single set packer to a measured depth of 4,630 feet; 3) setting the packer; 4) mixing and pumping the reformulated gel through the drill string to the 1,000 foot of open lateral below the packer; 5) pumping a wiper plug down the drill string to evacuate most of the pumped gel from the drill string displacing it below the packer into the lateral at about 500 psi; 6) waiting twenty-four (24) hours for the gel to cure; 7) coming off of the packer and tripping the drill string out of the lateral; 8) monitoring the mine-through of the plugged lateral following precautions established; and 9) evaluating the results. About 1,800 gallons of gel were displaced below the packer to fill the bottom 1,000 feet of the lateral. Mine-through occurred without incident as the lateral was filled with cured gel. A mechanical packer was installed after removing gel from the lateral at the coal rib with a roof bolt. Ambient methane concentration did not increase during the mine-through nor did water production. DD2 was put back on line with gas production resuming to its original 380 Mcfd prior to the plugging effort.
The illustration below shows the procedure Target Drilling would follow to plug an entire CBM well drilled implementing Target’s patented Under-Balanced Directional Method for CBM Dual Wells including all laterals. After reformulating the gel mixture to accommodate the water chemistry and reservoir pressure of the well, the bottom section of the steel casing would be milled and a packer equipped with one-way check valves and pressure transducer would be installed. The reformulated gel would be pumped through the drill string and below the packer monitoring gel injection pressure. After approximately 2 times the volume of reformulated gel was pumped into the laterals at the designed final injection pressure, the drill string would be pulled off of the packer leaving the packer in the steel casing above the mined coal. The steel casing in the Access Curve and Vertical Production well would be plugged with cement according to regulations afterwards.

See Also: Plugging In-Mine Boreholes with Polymer Gel

SURFACE CBM WELL LATERAL GELLED AND MINED INTO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PLUGGING A TARGET DRILLING SURFACE CBM WELL WITH GEL