Utilizing Innovative Flexible Sealant Technology in Rigless Plug and 
Abandonment

Barclay, Ian; Johnson, C. Anderson; Staal, Timo W.; Suresh, Choudhary; Abdulhameed, Al-Hamandani

doi:10.2523/89622-ms

Cited by 4 publications

(2 citation statements)

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“…According to several studies, 1,2,3,4 changes in downhole conditions lead to mechanical damage of the set cement behind the casing that can cause either direct mechanical failure of the system or the creation of microannuli. This problem, when attributed to sealant behind the casing, is mainly the result of the failure of this sealant to provide adequate zonal isolation.…”

Section: Introductionmentioning

confidence: 99%

Using a Flexible, Expandable Sealant System to Prevent Microannulus Formation in a Gas Well: A Case History

Johnson

Hegab

Rishmani

et al. 2005

SPE Middle East Oil and Gas Show and Conference

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractLong-term zonal isolation of gas reservoirs is a difficult problem. This paper summarizes the implementation and evaluation of a new sealant system designed to overcome this problem by preventing formation of a microannulus across the gas zone. A case history of its use in a well in the United Arab Emirates demonstrates the successful application of the flexible, expandable sealant material to prevent microannulus and maintain cement sheath integrity in the production casing section.In one well, a conventional cement slurry formulation was used for the 9 5/8-in. section. The section was then tested to 3,000 psi pressure. Cement-bond logs showed clear deterioration of cement sheath quality behind the casing. A similar result for upcoming casing sections was a concern, so the sealant was redesigned to accommodate downhole stresses across the interval. The new design, which was used in the 7in. liner section in the same well, enabled mechanical and expansion properties to be engineered to withstand downhole stresses and minimize the debonding effect. After successful isolation in the first well, the flexible, expandable sealant material was established as standard practice in similar wells.

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Section: Introductionmentioning

confidence: 99%

Using a Flexible, Expandable Sealant System to Prevent Microannulus Formation in a Gas Well: A Case History

Johnson

Hegab

Rishmani

et al. 2005

SPE Middle East Oil and Gas Show and Conference

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“…The following equation is used to calculate the coefficient of friction (Kb) in second and third round experiments: (6) The units in the equation must be consistent, for example:…”

Section: Unit Consistency In Equation To Calculate Coefficient Of Frimentioning

confidence: 99%

Plugging coal seam gas wells with bentonite

Mortezapour¹

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This thesis investigates the strength of hydrated bentonite plugs when used to plug and abandon coal seam gas wells and other oil and gas wells. A set of experiments was designed to measure the frictional strength between the steel casing walls and the hydrated plugs.The coefficient of friction between bentonite and steel casing was previously measured with Wyoming bentonite and found to be between 0.8 and 1.8, results that imply that friction is not the only force contributing to the plug strength (friction factor being bigger than 1). Calculations resulting from measurements in my experiments showed the coefficient of friction to be 1.92 for 0.0889 meter (3.5 inch) plugs and 5.5 for 0.1397 meter (5.5 inch) plugs. These coefficient of friction results suggest that the internal swelling forces should be considered as an additional term in the equation and more experimental work is required to evaluate internal swelling forces. Effect of swelling forces can be seen more in the larger plug sizes as the moisture content is higher and the calculated coefficient of friction is higher, in fact more than one.The relationship between the height of a bentonite plug and the pressure it can stand was investigated with a parabolic model, but, it has been postulated by different researchers to be both linear and parabolic. Because of experimental equipment limitations on casing size (plug size), the results of this research cannot lead to a clear conclusion on the relationship between the plug's height and its dislodgment pressure as the experimental results fit both the linear and parabolic models. Further work is needed on several different casing sizes to test the true relationship.The plug failure mode was found to be frictional for these experiments but shear failure is also possible in practice depending on the size of the hydrated plugs.The experimental results on monitoring the hydration of a plug with a middle hole of 0.0317 meter (1¼ inch) show that after 46 days of hydration time the middle hole has been filled in due to clay expansion. However, plug cuts show that more hydration time needed for middle of the plugs to be fully hydrated (Plugs were partially hydrated).The moisture content of the plugs after 48 days hydration were measured as 47% -53% and 28% -32% reducing with plug height for different plug sizes (0.0889 meter (3.5 inch) and 0.1397 meter (5.5 inch) dry plugs).3

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Plugging Wells with Hydrated Bentonite, Part 2: Bentonite Bars

Towler

Victorov²,

Zamfir³

et al. 2008

SPE Annual Technical Conference and Exhibition

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Data for the kinetics of the swelling of bentonite bars are shown and measurements for the friction factor between the hydrated bars and steel and plastic pipe are given. The results are compared with a previously derived equation for pressure containment. These results demonstrate that the bars produce a hydrated bentonite that has similar or better pressure containment than other bentonite solutions. Bentonite has long been used for the plugging of water wells and these bars have been produced for use in the plugging and abandonment of oil and gas wells. Introduction In a previous paper (Towler and Ehlers, 1997) the process for using bentonite (sodium montmorillinite) for plugging wells was described and an equation was derived for calculating the pressure that could be contained by a bentonite plug. The friction factor in this equation was determined from lab measurements. The process for plugging wells with bentonite is already widely used for shallow water wells in a variety of forms (James, 1996 and Wheaton et al. 1994) and has been gaining acceptance for plugging oil and gas wells (Clark and Salsbury, 2003, Idialu et al., 2004). The potential is that plugging wells with bentonite is much cheaper and more reliable than concrete plugs (Clark and Salsbury, 2003). It is claimed to be more reliable because concrete can fail to seal or later crack due to ground movement or tectonic activity. Hydrated bentonite, on the other hand, is deformable and hence self sealing in such circumstances. However one of the problems with the process is getting the bentonite to the bottom of the hole before it sets up. Simply pouring bentonite granules into the well tends to result in bentonite swelling and bridging soon after it hits the water column. This holds the bentonite at a site above where it needs to be. A solution to this problem is to compress the bentonite into bullet shaped bars using a suitable binder. This retards the hydration kinetics and allows the bentonite to be deposited to the correct plug location before the swelling occurs. In this paper bentonite pellets have been compressed into a bullet shape and then hydrated into a plug for sealing against steel casing. The pressure to dislodge this plug has been measured and used to determine the friction factor between the bentonite and steel. Literature review The costs to plug and abandon (P&A) a well can be substantial. Kaiser and Dodson (2008) have recently reviewed the P&A cost trends for the Gulf of Mexico and the average cost to abandon a well there has risen to $178,000 in 2007 up from $107,000 in 2002. The price would have been even higher if not for economies of scale and turn-key operations. Using day rates the cost of well abandonment has peaked at $235,000/well in 2006. The standard procedure for well abandonment has been well documented (Smith, 1993, Kelm and Faul, 1999, Calvert and Smith, 1994). In the oil and gas industry the standard procedure involves setting a cement plug across the perforations and at certain other intervals required to isolate critical zones. This has usually involved the use of a workover rig but recently coiled tubing units have become popular for reducing costs (Barclay et al., 2004, Chong et al., 2000, Tettero et al., 2004).

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Utilizing Innovative Flexible Sealant Technology in Rigless Plug and Abandonment

Cited by 4 publications

References 0 publications

Using a Flexible, Expandable Sealant System to Prevent Microannulus Formation in a Gas Well: A Case History

Using a Flexible, Expandable Sealant System to Prevent Microannulus Formation in a Gas Well: A Case History

Plugging coal seam gas wells with bentonite

Plugging Wells with Hydrated Bentonite, Part 2: Bentonite Bars

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