Page 393 - Practical Well Planning and Drilling Manual

Section 3 revised 11/00/bc 1/17/01 12:00 PM Page 369

3.3.5
Drilling Problems [ ]

2. Dimensions of the top of the fish with a view to latching on with
an overshot, spear, die collar, etc.
3. Weight and total length of the fish
4. Depth of the top of the fish
5. Whether the fish is stuck in the hole or if it should come free eas-
ily if latched on

If the condition of the top of the fish is unknown, a lead impres-
sion block (LIB) can be used to get an impression of the top of the fish.
The fish should only be tagged once with the LIB, otherwise conflict-
ing impressions are likely to be made. When the TOF is tagged, set
down 10,000-20,000 lbs and POH.
Fishing for small pieces of junk. There are several tools that will
catch bit cones and similar sized junk. A reverse circulating junk bas-
ket directs hydraulic flow onto the bottom and blows junk up into the
basket. Spring-loaded fingers allow the junk to enter but lock closed to
stop them from dropping out again.
The apple junk retriever is like a hollow cylinder run over the
junk. By dropping a ball and pressuring up against a seat, a set of fin-
gers is closed below the junk with sufficient force to cut a bit of a core
in softer formations. Excellent for recovering this kind of junk.
A mill tooth bit and junksub can sometimes drill up junk or push
it into the side of the hole. Quite effective in larger hole sizes/softer for-
mations. Drill on bottom with low WOB/RPM and high flow rate. Shut
off the pumps, pick up 10 m and go back to bottom. Repeat several
times. Small metal parts may fall into the junksub.
A flat-bottomed mill and junksub may be better than a mill tooth
bit in harder formations where the junk should stay put on bottom
while milling. Work the junksub as before. This may take some time if
the junk is able to roll around on bottom under the mill; pick up often
then go rotating back down. Setting some cement on bottom may hold
the junk in place long enough for you to mill it up.
Fishing for drillstring components and other tubular items
(catching outside). The best tool is the overshot. It is simple to run,
can exert tremendous pull on the fish, be jarred with and yet released
easily. It can also apply LH torque to backoff the fish lower down. Refer
to the Bowen section of the Composite Catalog or to the Bowen manu-
als for comprehensive information on the tool.

369