Development and Use of a Gas-Tight Cement

Grinrod, M.; Vassoy, B.; Dingsøyr, E.

doi:10.2118/17258-ms

Cited by 18 publications

(5 citation statements)

References 4 publications

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“…(Fig.1). Microsilica (Grinrod et al, 1988) is a byproduct derived from the production of silicon and ferrosilicon alloys. These alloys are produced in large electrical furnaces.…”

Section: Reduced Internal Permeabilitymentioning

confidence: 99%

A Successful Field Experience: Shallow Water Flow—How to Avoid the Need for an Additional Casing String

Pedersen

Taoutaou

Watts

et al. 2008

IADC/SPE Drilling Conference

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In areas with shallow water flow, additional casing strings are normally set to seal off the water-bearing zone. While drilling the first well in Fram East in the North Sea, the operator used a shallow 20-in. surface casing, but this measure increased well costs and caused a number of later limitations in the well construction process. To avoid these complications in other Fram East wells, the operator searched for alternative solutions.It selected a cement design with properties compensating for the loss of hydrostatic pressure and thereby preventing the water flowing. The service company carried out extensive designing and testing of the cement formulations. A major challenge was qualifying the final design for a full-scale field test. A third-party laboratory qualified the cement system, using a modified setup of the gas migration equipment. The results were promising.A dedicated cutting injection well was chosen for the field test. The successful test allowed planning the remaining wells using the new system with projected savings of more than USD 20 million. This paper will describe the development of the solution, the design, and testing of the cement formulation, and the full-scale field test performed. IntroductionThe main objective of the cement is to provide a hydraulic seal across the various permeable formations; zonal isolation is compromised when formation fluids such as water are allowed to enter the annulus. During and after the placement, the cement column and the other fluids in the wellbore or annulus exert a hydrostatic pressure that initially must be greater than the formation pore pressure to prevent invasion of formation fluids. However, as the cement hydrates, the cement slurry becomes self-supporting and the hydrostatic pressure exerted by the slurry decreases. When the hydrostatic pressure decreases below the formation pore pressure, formation fluids such as water can enter the annulus, potentially leading to water flow through the cement matrix, which leads to the loss of hydraulic isolation.

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“…(Fig.1). Microsilica (Grinrod et al, 1988) is a byproduct derived from the production of silicon and ferrosilicon alloys. These alloys are produced in large electrical furnaces.…”

Section: Reduced Internal Permeabilitymentioning

confidence: 99%

A Successful Field Experience: Shallow Water Flow—How to Avoid the Need for an Additional Casing String

Pedersen

Taoutaou

Watts

et al. 2008

IADC/SPE Drilling Conference

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“…(Ref. 3,8,10). The 14 lbm/gal slurry in use displays an increase in internal permeability of the hydrating cement relative to lower water ratio cements.…”

Section: Early Successmentioning

confidence: 99%

Effective Slimhole Cementing in a Challenging Environment - A Gulf of Thailand Case History

Todd¹,

Harrison²,

Duantem³

et al. 2001

Proceedings of SPE Asia Pacific Oil and Gas Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe successful development of a light weight slurry system for cementing long intervals at high temperatures in three dimensional multiple stacked gas zone wells, has been achieved in the Gulf of Thailand. The cementing system has been developed to successfully complete progressively more difficult wells, starting with conventional large bore wells and tubing plus packer completions, and later down-sizing into single monobore wells whereby the tubing is cemented in place. The problems associated with the down-sizing of the wells are further increased by more challenging well paths and higher temperature fields. Many problems and risks were overcome to complete this task successfully. These changes have posed new challenges in primary cementing.Like the well size, the slurry system has also undergone a refinement and improvement process. The local industry has gone from dry blended slurry systems to all-liquid additive slurry systems saving considerable dollars, whilst realizing large gains in slurry flexibility, ease of mixing and improved logistics. Whilst developing and realizing these gains, the system has been refined and successfully applied to smaller, hotter and more difficult wells.This paper presents the concerns associated with cementing these challenging wells where remedial cementing has been effectively eliminated. The processes related to this success, evaluation methods and field results will be discussed.

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“…The cement sheath should possess an ultra-low permeability to mitigate and prevent gas migration to other formations and to the surface. To achieve this, several additives can be mixed with the Portland cement to formulate a gas-tight slurry [16][17][18][19]. Also, the use of geopolymers as a replacement of Portland cement can enhance the cement integrity [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Analytical and Experimental Investigation of the Critical Length in Casing–Liner Overlap

et al. 2019

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Offshore drilling operations exhibit various difficulties attributed to shallow flows worldwide. One of the most common practices for drilling offshore wells is to use liners and liner hangers rather than using full casing strings. This reduces the cost of drilling operation. Liners and liner hangers are required to pass certain standards prior to their deployment in the field. This ensures their ability to withstand harsh downhole conditions and maintain the integrity of the well. A liner hanger contains an integrated seal assembly that acts as a barrier to prevent fluid migration. The cement that is placed within the casing–liner overlap is also considered a barrier, and it is critical that it maintains the integrity of the well by mitigating fluid migration to other formations and to the surface. The failure of this dual barrier (cement and seal assembly) system to seal the annular space can result in serious problems that might jeopardize a well’s integrity. Typically, in field applications, the length of a casing–liner overlap is chosen arbitrarily. In some cases, shorter overlaps (50 to 200 ft) are chosen because of the lower cost and easy identification of leaks during pressure tests. However, some loss of well control incidents (particularly the incident that motivated this study) have been linked to fluid leakages along the casing–liner overlap. This paper investigates the critical length of the casing–liner overlap by modeling gas leakage through the cement placed within the overlap using analytical and experimental approaches. Leakage scenarios were developed to mimic gas migration within the cement in the casing–liner overlap. The results showed that the longer the casing–liner overlap, the higher the leakage time. The results also showed that the current casing pressure test duration of 30 min may not be adequate to verify the integrity of the cement within the overlap. Based on the results and analyses, it is recommended to increase the pressure test duration to 90 min. In addition, the results suggest that the length of the casing–liner overlap should not be less than 300 ft to maintain the integrity of the well in the case of gas influx. Further details are highlighted in the results section. In practice, the current rationale behind the selection of a casing–liner overlap length is not sustainable. Thus, the major advantage of this study is that with field data, it provides both scientific and research-based evidence that can be used to inform the decision behind the selection of the casing–liner overlap length, especially in gas migration-prone zones.

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Development and Use of a Gas-Tight Cement

Cited by 18 publications

References 4 publications

A Successful Field Experience: Shallow Water Flow—How to Avoid the Need for an Additional Casing String

A Successful Field Experience: Shallow Water Flow—How to Avoid the Need for an Additional Casing String

Effective Slimhole Cementing in a Challenging Environment - A Gulf of Thailand Case History

Analytical and Experimental Investigation of the Critical Length in Casing–Liner Overlap

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