The authors would like to thank the following people and institutions for their help and support: William Portas and James Heathman (Industry Advisors, Shell E&#38;P), Richard Littlefield and Rodney Pennington (Shell Westhollow Technology Center), Daniele di Crescenzo (Shell Research Well Engineer), Bill Carruthers (LaFarge), Tim Quirk (now with Chevron), Gerry Masterman and Wayne Manuel (LSU PERTT Lab), Rick Young (LSU Rock Mechanics Lab), and members of the SEER Lab (Arome Oyibo, Tao Tao, and Iordan Bossev).

1. Composite Sample (Figure 1)
NOTE: Most cement jobs in the Gulf of Mexico (USA) are done using Class H cement18, therefore, the same type of cement was used to perform the lab experiments to simulate field-like conditions, the potential applicability of this technology for SCP remediation in the Gulf of Mexico.
<ol>
	<li>Sample preparation 
	NOTE: The 61-cm long sample consists of two grade B electrically resisted welded (ERW) carbon steel pipes (Figure 1)....

<ol>
	<li>King, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Well+Integrity:+Hydraulic+Fracturing+and+Well+Construction+&#8211;+What+are+the+Factual+Risks.">Well Integrity: Hydraulic Fracturing and Well Construction &#8211; What are the Factual Risks.</a> SPE Wellbore Integrity Webinar. 5, (2013).</li><li>Taylor, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cement Chemistry. , (1997).</li><li>Thiercelin, M. J., Dargaud, B., Baret, J. F., Rodriguez, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cement+design+based+on+cement+mechanical+response.">Cement design based on cement mechanical response.</a> SPE Drill &amp; Compl. 13 (4), 266-273 (1998).</li><li>Nelson, E. B., Guillot, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Well Cementing. , (2006).</li><li>Carter, L., Evans, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Study+of+Cement-Pipe+Bonding.">A Study of Cement-Pipe Bonding.</a> Paper SPE 164 presented at the California Regional Meeting. , 24-25 (1964).</li><li>Goodwin, K., Crook, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cement+Sheath+Stress+Failure.">Cement Sheath Stress Failure.</a> SPE Drill Eng. 7 (4), 291-296 (1992).</li><li>Heathman, J., Beck, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Finite+Element+Analysis+Couples+Casing+and+Cement+Designs+for+HP/HT+Wells+in+East+Texas.">Finite Element Analysis Couples Casing and Cement Designs for HP/HT Wells in East Texas.</a> Paper SPE 98869 presented at the IADC/SPE Conference. , (2006).</li><li>Boukhelifa, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+Cement+Systems+for+Oil+and+Gas+Well+Zonal+Isolation+in+a+Full-Scale+Annular+Geometry.">Evaluation of Cement Systems for Oil and Gas Well Zonal Isolation in a Full-Scale Annular Geometry.</a> Paper SPE 87195 presented at the IADC/SPE Drilling Conference. , (2004).</li><li>Duan, S., Wojtanowicz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Method+for+Evaluation+of+Risk+of+Continuous+Air+Emissions+from+Sustained+Casinghead+Pressure.">A Method for Evaluation of Risk of Continuous Air Emissions from Sustained Casinghead Pressure.</a> Paper SPE 94455 presented at SPE/EPA/DOE Exploration and Production Environmental Conference. , (2005).</li><li>Watson, T. L., Bachu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+potential+for+gas+and+CO2+leakage+along+wellbores.">Evaluation of the potential for gas and CO2 leakage along wellbores.</a> SPE Drill &amp; Compl. 24 (1), 115-126 (2009).</li><li>Wojtanowicz, A. K., Nishikawa, S., Xu, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+and+remediation+of+SCP+in+wells.">Diagnosis and remediation of SCP in wells.</a> Final report submitted to US Department of Interior MMS. , (2001).</li><li>Kupresan, D., Heathman, J., Radonjic, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Assessment+of+Casing+Expansion+as+a+Solution+to+Microannular+Gas+Migration.">Experimental Assessment of Casing Expansion as a Solution to Microannular Gas Migration.</a> Paper SPE 168056 presented at IADC/SPE Drilling Conference and Exhibition. , (2014).</li><li>Kupresan, D., Heathman, J., Radonjic, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+a+New+Physical+Model+of+Expandable+Casing+Technology+in+Mitigation+of+Wellbore+Leaks.">Application of a New Physical Model of Expandable Casing Technology in Mitigation of Wellbore Leaks.</a> CETI Journal. 1 (5), 21-24 (2013).</li><li>Demong, K., Rivenbark, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breakthroughs+using+Solid+Expandable+Tubulars+to+Construct+Extended+Reach+Wells.">Breakthroughs using Solid Expandable Tubulars to Construct Extended Reach Wells.</a> Paper SPE 87209 presented at the IADC/SPE Drilling Conference. , (2004).</li><li>Grant, T., Bullock, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+evolution+of+Solid+Expandable+Tubular+Technology:+Lessons+Learned+Over+Five+Years.">The evolution of Solid Expandable Tubular Technology: Lessons Learned Over Five Years.</a> , (2005).</li><li>Jennings, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+formations+rendered+less+problematic+with+solid+expandable+technology.">Dynamic formations rendered less problematic with solid expandable technology.</a> , (2008).</li><li>Fanguy, C., Mueller, D., Doherty, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+method+of+cementing+solid+expandable+tubulars.">Improved method of cementing solid expandable tubulars.</a> , (2004).</li><li>American Petroleum Institute. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Appendix+C+(tentative),+Fluid+Density+Balance.">Appendix C (tentative), Fluid Density Balance.</a> Recommended Practice for Testing Oilwell Cements and Cement Additives. , (1971).</li><li>Nelson, E. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Well cementing. , (1990).</li></ol>

The authors have nothing to disclose.

The reported experimental procedure has two main components that are critical: composite cylinders that simulate wellbores and the expansion fixture that is used to carry out mechanical manipulation of cement. When designing wellbore models (cement/pipe composite cylinders), it is critical to choose adequate cement density, store samples under total humidity conditions (100% RH) and establish pipe-cement debonding before cement slurry completely sets. Failing to achieve this would make the entire gas flow experiment impo...

The reported experimental procedure has two main components that are critical: composite cylinders that simulate wellbores and the expansion fixture that is used to carry out mechanical manipulation of the cement.
Wellbores are the main gateway for production of subsurface fluids (water, oil, gas, or steam) as well as injection of various fluids. Regardless of its function, the wellbore is required to provide a controlled flow of produced/injected fluids. Wellbore construction has two distinct operations: drilling and completion. Wellbore cement, part of the completions procedure, primarily provides zonal isolation, mechanical support of the metal pipe (casing), and protection of metal components from corrosive fluids. These are essential elements of uncompromised, fully functioning wellbores. The integrity of the wellbore cement sheath is a function of the chemical and physical properties of the hydrated cement, the geometry of the cased well, and the properties of the surrounding formation/formation fluids2,3. Incomplete removal of drilling fluid will result in poor zonal isolation since it prevents formation of strong bonds at interfaces with rock and/or metal. Cement sheaths can be subjected to many types of failure during the life of a well. Pressure and temperature oscillations caused by completion and production operations contribute to the development of fractures within the cement matrix; debonding is caused by pressure and/or temperature changes and cement hydration shrinkage4,5,6. The result is almost always presence of microannular fluid flow, although its occurrence can be detected early or after years of service life.
Heathman and Beck (2006) created a model of cemented casing subjected to over 100 pressure and temperature cyclic loads, which showed visible debonding, initiation of cement cracks which can pose preferential pathways for migrating fluid7. In the field, the expansion and contraction of metal components of a wellbore will not coincide with those of cement and rock, causing interfacial debonding and formation of a microannulus, leading to an increase in permeability of the cement sheath. An additional casing loading can cause the propagation of radial cracks in the cement matrix once the tensile stresses exceed the tensile strength of the material8. All of the aforementioned cement failures can result in micro-channeling, which leads to gas migration, the occurrence of SCP, and long-term environmental risks.
A considerable number of producing and abandoned wells with SCP constitute a potentially new source of continuous natural gas emission9. The analysis conducted by Watson and Bachu (2009) of 315,000 oil, gas, and injection wells in Alberta, Canada also showed that wellbore deviation, well type, abandonment method, and the quality of cement are key factors contributing to potential well leakage in the shallower part of the well10. The existing remedial operations are costly and unsuccessful; the squeeze cementing, one of the most commonly used remedial techniques, has a success rate of just 50%11.
In this paper we report on the evaluation of the Expandable Casing Technology (ECT) as a new remediation technique for leaky wellbores12,13. ECT can be applied in new or existing wells14. The first commercial installation of this technology was performed by Chevron on a well in shallow waters of the Gulf of Mexico in November 1999 15. The current operating envelope for expandable tubulars encapsulates an inclination of 100&#176; from vertical, temperature up to 205 &#176;C, mud weight to 2.37 g/cm3, a depth of 8,763 m, hydrostatic pressure of 160.6 GPa and a tubular length 2,092 m 16. A typical expansion rate for solid expandable tubulars is approximately 2.4 m/min 17.
This study offers a unique approach to the adaptation of ECT technology as a new remediation operation for SCP. The expansion of the steel pipe compresses the cement which would result in closure of the gas flow at the interface and seal the gas leak. It is important to mention that the focus of this study is the sealing of an existing microannular gas flow, therefore we only focused on that as a possible cause of leaky wellbores. In order to test the effectiveness of newly adapted technology for this purpose, we designed a wellbore model with an existing microannular flow. This is obtained by rotating the inner pipe during cement hydration. This is not to simulate any field operations, but simply to fast-forward what would happen after decades of thermal and pressure loading in a wellbore.

<table border="0" cellpadding="0" cellspacing="0" width="742">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:341px;">ASTM A53 Grade B ERW Schedule 40 Steel pipe - OD=10.16 cm, ID=10.04 cm, L=59.7 cm</td>
			<td style="width:108px;">Baker Sales</td>
			<td style="width:119px;">BPE-4.00BB40</td>
			<td></td>
		</tr>
		<tr height="50">
			<td height="50" style="height:50px;width:341px;">ASTM A53 Grade B ERW Schedule 10 Steel pipe - OD=6 cm, ID=5.94 cm, L=61 cm&#160;</td>
			<td style="width:108px;">Service Steel</td>
			<td style="width:119px;">n/a</td>
			<td></td>
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		<tr height="42">
			<td height="42" style="height:42px;width:341px;">Expansion Cones - AISI D2 grade alloy steel (60 RC hardness)</td>
			<td style="width:108px;">Shell</td>
			<td style="width:119px;">Custom-made</td>
			<td></td>
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		<tr height="37">
			<td height="37" style="height:37px;width:341px;">Pipe coupling - OD=6.35 cm, ID=6 cm, L=4.4 cm</td>
			<td style="width:108px;">LSU</td>
			<td style="width:119px;">Custom-made</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:341px;">Steel plate ring - OD=10.16 cm, ID=5.76 cm, thickness=6.35 mm</td>
			<td style="width:108px;">Louisiana Cutting</td>
			<td style="width:119px;">Custom-made</td>
			<td></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:341px;">Class H Cement</td>
			<td style="width:108px;">LaFarge</td>
			<td style="width:119px;">04-16-12 / 14-18</td>
			<td></td>
		</tr>
		<tr height="32">
			<td height="32" style="height:32px;width:341px;">Defoaming agent - D-Air 3000L</td>
			<td style="width:108px;">Halliburton</td>
			<td style="width:119px;">n/a</td>
			<td></td>
		</tr>
		<tr height="30">
			<td height="30" style="height:30px;width:341px;">Bentonite clay</td>
			<td style="width:108px;">LSU</td>
			<td style="width:119px;">n/a</td>
			<td></td>
		</tr>
		<tr height="30">
			<td height="30" style="height:30px;width:341px;">Calcium hydroxide</td>
			<td style="width:108px;">LSU</td>
			<td style="width:119px;">n/a</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:341px;">Expansion Fixture</td>
			<td style="width:108px;">Shell</td>
			<td style="width:119px;">Custom-made</td>
			<td></td>
		</tr>
		<tr height="29">
			<td height="29" style="height:29px;width:341px;">Pressure transducers</td>
			<td style="width:108px;">Omega</td>
			<td style="width:119px;">PX480A-200GV&#160;</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:341px;">Teflon tubing</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">PB0754100</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:341px;">Union tee</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">SS-400-3</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:341px;">Elbow union</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">SS-400-9</td>
			<td></td>
		</tr>
		<tr height="29">
			<td height="29" style="height:29px;width:341px;">Female elbow</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">SS-400-8-8</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:341px;">Port connector</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">SS-401-PC</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:341px;">Forged body valve</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">SS-1RS4</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:341px;">Tube adapter</td>
			<td style="width:108px;">Swagelok</td>
			<td style="width:119px;">SS-4-TA-1-2</td>
			<td></td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:341px;">Pipe lubricant</td>
			<td style="width:108px;">E.F. Houghoton &#38; Co.</td>
			<td>71323998</td>
			<td></td>
		</tr>
		<tr height="30">
			<td height="30" style="height:30px;width:341px;">Instant Galvanize Zinc Coating</td>
			<td style="width:108px;">CRC</td>
			<td style="width:119px;">78254184128</td>
			<td></td>
		</tr>
	</tbody>
</table>

mechanical expansion of steel tubing as a solution to leaky wellbores

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe (casing), and protects metal components from corrosive fluids. These are essential for uncompromised wellbore integrity. Cements can undergo multiple forms of failure, such as debonding at the cement/rock and cement/metal interfaces, fracturing, and defects within the cement matrix. Failures and defects within the cement will ultimately lead to fluid migration, resulting in inter-zonal fluid migration and premature well abandonment. Currently, there are over 1.8 million operating wells worldwide and over one third of these wells have leak related problems defined as Sustained Casing Pressure (SCP)1. 
The focus of this research was to develop an experimental setup at bench-scale to explore the effect of mechanical manipulation of wellbore casing-cement composite samples as a potential technology for the remediation of gas leaks. 
The experimental methodology utilized in this study enabled formation of an impermeable seal at the pipe/cement interface in a simulated wellbore system. Successful nitrogen gas flow-through measurements demonstrated that an existing microannulus was sealed at laboratory experimental conditions and fluid flow prevented by mechanical manipulation of the metal/cement composite sample. Furthermore, this methodology can be applied not only for the remediation of leaky wellbores, but also in plugging and abandonment procedures as well as wellbore completions technology, and potentially preventing negative impacts of wellbores on subsurface and surface environments.

Pre-expansion gas flow-through tests on the composite sample showed pressure recording on the outlet pressure transducer, confirming gas flow through the pre-manufactured microannulus (Figures 7 and 8). Initial conditions were kept the same where initial inlet pressure was 103 kPa and the gas flow rate was kept at 85 ml/min for that period. The time lag in pressure recording between the inlet and outlet pressure transducers was 7.5 seconds, while the highest pressures recorded after incr...

Watch this Scientific Journal Video about Mechanical Expansion of Steel Tubing as a Solution to Leaky Wellbores at JoVE.com

Mechanical Expansion of Steel Tubing as a Solution to Leaky Wellbores

This article reports on a laboratory scale investigation of an existing field procedure and its adaptation for sealing of leaky wellbores. It consists of mechanical expansion of metal pipe, which results in an improved metal/cement bond, ultimate sealing of hydraulic pathways and prevention of gas leaks caused by the presence of a microannular channel.

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe ...

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12.1K 조회수.  Louisiana State University. This article reports on a laboratory scale investigation of an existing field procedure and its adaptation for sealing of leaky wellbores. It consists of mechanical expansion of metal pipe, which results in an improved metal/cement bond, ultimate sealing of hydraulic pathways and prevention of gas leaks caused by the presence of a microannular channel.