Mechanical Expansion of Steel Tubing as a Solution to Leaky Wellbores

The overall goal of this procedure is to test the ceiling of micro annular gas flow in a model of a leaky well bore by expanding its inner pipe. This is accomplished by first creating a composite cement model system. The second step is to perform flow through experiments to demonstrate the existence of micro annular gas flow.

Next place the system in an expansion setup to expand the inner pipe. The final step is to perform additional flow experiments to test the effect of the inner pipe expansion. Ultimately, gas flow through experiments demonstrate the effectiveness of pipe expansion in sealing of the micro annular gas flow.

The main advantage of this technique or existing methods like que cementing, is that it requires less time. It has a higher success rate, and it has already been proven for drilling applications in the field. The implications of this technology are potentially huge as it can prevent contamination of subsurface freshwater aquifers from the hydrocarbons released, as well as release of hydrocarbons into the atmosphere.

Construct the sample from two grade B electric resistance welded steel pipes. Focus on the larger outer pipe, drill holes in it to provide pressure release and mimic rock porosity. In addition, evenly space four holes with 3.2 millimeter MPT threading tips around the top and bottom of the pipe to allow connecting pipe fittings.

Next, fabricate a custom made steel coupling for the two pipes. The coupling has a ring for attaching the outer pipe and threads for securing the inner pipe. After threading the inner pipe to connect with the coupling, make sure to check the fit.

Remove the pipe before proceeding. Continue After welding the anti corrosion treated outer pipe to the steel plate ring, screw the lubricated inner pipe into the coupling to finish the composite sample assembly. After this, the assembly is ready to have a cement slurry added between the pipes.

It will then be manipulated to create a microchannel and cured for experimentation. Weigh out an appropriate amount of water, cement and bentonite. Then add them to a blender cover and mix using the high setting for 40 seconds.

Once the slurry is well mixed, pour it into the assembly and follow steps in the accompanying text protocol. In order to properly cure the cement while creating microchannels, begin with an appropriately cured cemented composite assembly. Screw 3.2 millimeter fittings into the four inlet ports at the bottom of the outer pipe.

Do the same for the outlet ports at the top. Next, connect inlet and outlet manifolds with pressure transducers to the fittings. Now connect the inlet manifold at the bottom of the sample to a cylinder with pressurized nitrogen gas.

Ensure the flow valve is closed and increase the cylinder inlet pressure to 50 kilopascals. Prepare a computer to record the pressure transducer readings. Begin gas flow to start the flow through.

Test on the computer. Monitor the inlet and outlet pressures of the sample for one minute. Then increase the gas cylinder inlet pressure to 172 kilo pascals.

Monitor the pressures for another two minutes. When done, stop the pressure recording. Close the gas cylinder and vent the remaining gas into the atmosphere.

To prepare for the expansion procedure first, remove all of the manifolds from the outer cylinder. When done, coat the inside wall of the inner tube with lubricant. Also cover the top of the sample with a wet cloth to prevent carbonation and drying of the cement.

The expansion procedure will take place in a housing that can be accessed by an opening at the top. At one end is an expansion mandu that can be coupled to a hydraulic unit, completely retract the mandrel to allow the placement of the composite sample. Orient the composite sample so its bottom is toward the retracted expansion mandrel.

Place the composite sample in the housing. Then identify an expansion cone with the desired expansion ratio. This experiment will use a cone with a ratio of 8%Now fully elongate the expansion mandrel through the sample, and then slip the expansion cone onto it.

Next, screw the retaining mandrel onto the expansion mandrel. Complete the preparation by screwing the retaining manl guide onto the lower connector of the lower housing. Once everything is ready, power the hydraulic unit to an optimum pressure of 10.3 megapascals.

Prepare the computer to collect axial force data. Activate the control to retract the expansion manl and pull the expansion cone through the inner pipe of the sample. Expand the sample from one end to a length of 40.64 centimeters.

Then elongate the expansion mandrel into its original position. Stop the recording of the axial forces and prepare to retrieve the sample. Unscrew the retaining mandl guide and remove the retaining mandrel.

Take off the expansion cone from the expansion mandrel, and then fully retract the mandrel. Finally, remove the sample from the housing. After the expansion procedure, prepare the sample for more flow through experiments.

Be sure to clean the inlet and outlet ports of any excess of squeezed cement paste. When this is done, once again, attach the pipe fittings, manifolds with transducers and nitrogen cylinder. Set up the computer to record the transducer pressures.

Set the gas cylinder inlet pressure to 172 kilopascals. Open the flow meter and begin the flow through. Test monitor the inlet and outlet pressures on the computer screen for five minutes.

Next, change the gas cylinder inlet pressure to 345 kilopascals and monitor the pressures in the samples for another five minutes. Then increase the inlet pressure to 517 kilo pascals. Continue to monitor the pressures after five minutes, increase the inlet pressure to the final value of 690 kilo pascals and monitor for five minutes.

After five minutes at 690 kilopascals, end pressure recording and close the gas cylinder. Ben, the remaining gas into the atmosphere. Remove the manifolds from the sample.

This plot of pressure versus time shows both the inlet pressure in blue and the outlet pressure in red. This pre-expansion gas flow through test confirms gas flow through the pre-manufactured micro annulus starting at 100 seconds, the initial inlet pressure from the gas cylinder was 103 kipa cals, and the gas flow rate was 85 milliliters per minute. At 160 seconds, the gas cylinder pressure was increased to 172 kilopascals leading to the change in pressure at both the inlet and outlet.

The variation of pressure at the outlet is more clearly seen in this plot of log pressure versus time. Data from the pre-expansion tests give a micro annulus effective permeability of 0.66 Darcy. These are the results of a second flow through test.

After imposing an 8%expansion ratio on the composite sample, the pressure was increased gradually from 172 kilopascals to a final pressure of 690 kilo pascals every five minutes. No pressure was recorded on the outlet pressure transducer. The test was repeated after 24 hours and after 60 days with the same result confirming that the 8%expansion rate was successful.

In closing the micro annular gas flow in the well bore model Once tested in the field, this technique can be effectively done in minutes and prevent negative environmental impacts of hydrocarbon leakage. So after watching this video, I hope you have a really good understanding how an adaptation of existing field technology can be used to prevent leakage of gas and oil in well Bos, not only in traditional oil and gas production, but also in carbon sequestration as well as in hydraulic fracturing.