7" Fullbore safety joint RTTS Drill stem testing tools(DST)

DST 7" Fullbore safety joint RTTS

Back Off Procedure

1. Part the tension sleeve (25,000 pounds for the 7"), if this has not already been done while trying to unseat the packer.

2. Using the weight indicator, locate the work string free point reading. Free point weight reading will be defined as where no string weight is setting down on the packer, and no over pull into the packer.  Do this a number of times to make sure of the correct free point weight reading. Mark the pipe number 1 at the rotary table.  

3. Pull up until the weight indicator shows some over pull above the string free point reading. Repeat this procedure a number of times to confirm this point.  Mark the pipe number 2 at the rotary table.

4. Slack back off to the string free point number 1.

5. Slack off the string until the weight indicator starts losing weight. Repeat this procedure a number of times to confirm this point. Mark the pipe number 3 at the rotary table.

6. Pull back up to the string free point number 1. The three marks made on the pipe will be used as reference points while backing off the back off (left hand) nut.

7. Set the slips and apply to the string the same number of right hand turns (at least 3 turns at 10,000 ft.) with the rotary table that was used to set the packer (assuming 5" drill pipe and a straight hole). Use the make up tongs to hold this torque (using snubber line) in the pipe while the slips are removed. Continue picking up until mark number 3 is at the rotary table. Enough snubber line must be use to allow for the free travel of the tongs as described below.

8. Slack off the string until mark number 2 is at the rotary table.

9. Work the string a number of times, while holding torque, up to point number 3 and down to point number 2 until the make up tongs become slack.  Observe the weight indicator reading while working the string to the reference marks to confirm setting down and picking up string weight above and below the string free point.

10. Repeat steps number 6 through number 9 until the safety joint is released.  As you back off the safety joint the reference marks will begin to move up slightly in relation to the rotary table.

Tension Sleeve

The DST tools manufactured by ZZ Top is full bore type and annular pressure operated, applicable for 4 1/2" to 20" casing, the tools OD is 3 7/8" and 5", Working pressure upto 105Mpa, working temperature upto 425F.

As per NACE MR0175 standard, the materials ZZ Top used is AISI41XX Alloy steel with hardness in 30HRC in average but also consider the high working pressure to choose high hardness material used in Critical parts i.e. Nitrogen Case, for ball valve, the material is Inconnel 718 which import from USA directly.

And for strict working condition such as high H2S, CO2, Acid and HCL, we also suggest the material Inconnel or other high Nickel alloy steel.

For other redress parts like O rings, rupture discs are also optional from US parker and Fike USA, and as per our test Chinese are also in good performance, those parts can be avaible once request.

Regarding DST tools, the maintenance is very important for each well running, replace all O rings after a job is very necessary to keep tools in well condition, ZZ Top also provide DST maintenance training in user site and in factory.

ZZ Top is running under ISO9001:2008, and all tools were certified by SGS in full process, from material to final function testing.

7" Fullbore safety joint RTTS Drill stem testing tools(DST)

DST 7" Fullbore safety joint RTTS