Preventing Shallow Gas Migration in Offshore Wells: The Performance of Lead Cements

Coker, Oliver D.; Williams, Troy

doi:10.2118/24978-ms

Cited by 6 publications

References 7 publications

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Durability of lightweight oil-well geopolymer system in sulfate environment

Adjei

Abdelaal

Elkatatny

et al. 2022

J Petrol Explor Prod Technol

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Sulfates when present in the formation water would attack and deteriorate the cementitious system. In the quest to investigate the possibility of using geopolymer systems in oil-well cementing, the durability of geopolymer in various corrosive environments has been simulated. Lightweight geopolymer systems exhibit different microstructural and macroscopic properties compared to the conventional geopolymer systems whose durability under sulfate attack has been widely investigated. It is therefore important to study the resistance of lightweight geopolymer to sulfate attack. A ternary geopolymer was formulated at 13 ppg (1.56 g/cm3) by admixing metakaolin, ground granulated blast furnace slag (GGBFS), and silica fume in an alkaline solution composed of sodium silicate and 10 M sodium hydroxide solution in a mass ratio 1:3. The geopolymer specimen was cured in a water bath at 163 °F for 72 h and subsequently submerged in a 50 g/L sodium sulfate solution for up to 2 days. The effect of the sulfate solution on the strength and the mechanism of the sulfate attack was analyzed using analytical techniques, pH, and ion exchange measurements. The compressive strength of the specimen at 72 h, having a value of 802 psi decreased by 19.8% and 26.2% after day 1 and day 2 in the sodium sulfate solution, respectively. Investigation of the mechanism indicated that the loss in strength was not a result of the formation of deleterious phases but rather the leaching of Na ions from the geopolymer indicated by the rise in the pH and amount of Na ions in the sodium sulfate solution after the geopolymer was submerged in a sulfate solution. Lightweight geopolymer has a relatively loose microstructure that reduces its tendency to inhibit the transport of alkalis during sulfate attack, making the effect of the sulfate environment more pronounced.

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Durability of lightweight oil-well geopolymer system in sulfate environment

Adjei

Abdelaal

Elkatatny

et al. 2022

J Petrol Explor Prod Technol

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Evaluation of Precompletion Annular Gas Leaks in a Marcellus Lateral

et al. 2012

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Environmental concerns in Pennsylvania related to Marcellus Shale development are high. One of the issues to which the Pennsylvania Department of Environmental Protection (PADEP) has given a high priority is the threat of methane migration into fresh water as a result of methane leaking to surface from behind casing. This has become a significant problem for Marcellus operators as leaking annuli on both new and existing wells is not uncommon. This paper outlines the steps that Flatirons Development took to demonstrate to PADEP that the annular leaks on a recently drilled and cased Marcellus lateral posed no credible threat to ground water and that completion of the well should be allowed to proceed. In early June, 2011, Flatirons became aware of bubbling in the water filled cellar of the DU 3-6-1H. This discovery came just as completion operations were set to begin. Subsequent investigation revealed that there were two leaks, one from the production-intermediate annulus and another very small leak from the intermediate-surface annulus. PADEP issued Flatirons a Notice of Violation (NOV) and requested that fracture treating the well not proceed until the issue had been resolved. Over the following two months, Flatirons implemented a series of diagnostic procedures meant to assess the short and long term environmental threat, determine the cause of the problem, trace the source of the gas, and, if necessary, formulate effective remediation options. Using a variety of tools including ultrasonic imaging, pressure build-ups, noise-temperature logs, gas isotopic analysis, cement sample analysis, and continuous monitoring of annular flow, Flatirons was able to demonstrate that the fresh water aquifer was not threatened by methane migration. This work was presented to PADEP's Gas Well Integrity study group and helped form a basis for revising regulations governing leaking annuli.

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Evaluation of Zonal Isolation Material for Low Temperature Shallow Gas Zone Application

Agista

Khalifeh

Saasen

2022

SPE Asia Pacific Oil &Amp; Gas Conference and Exhibition

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Methane gas leaks from shallow gas zone have been reported in some areas in the North Sea. In the North Sea, shallow gas zones can have temperatures below 25°C with relatively low pore pressure. It is necessary to prevent the flow of this gas behind casings by performing proper zonal isolation with cementitious materials. A series of experiments were performed on three different types of industrially used and state-of-the-art cementitious materials and a rock-based geopolymer to evaluate their performance for shallow gas zonal isolation. Neat class G Portland cement, industrial rapid-hardening cement, gas-tight cement, and granite-based geopolymer were the selected materials. The research aims to reveal the performance of these zonal isolation materials and their potential shortcomings due to the low-temperature effect. Material characterizations were performed on three states of the materials: liquid-state, gel phase, and solid-state. Rheological properties and consistency are evaluated at the liquid state of the materials. Static gel strength tests were performed to evaluate the strength of gel structure and transition time. The compressive strength of samples was evaluated using an ultrasonic cement analyzer (UCA) and unconfined compressive strength (UCS). In addition, the scanning electron microscopy (SEM) technique was utilized to reveal microstructure of the materials. To have a similar hydration process as in the low-temperature shallow gas zone, slurries were mixed and pre-conditioned at temperatures of 4 and 25°C. The experiment shows that the hydration process of the cement is less optimum in the low-temperature condition, which affects the gel strength development of the cement during the transition from liquid to a solid phase. It also resulted in the lower final compressive strength of the cured specimens.

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Preventing Shallow Gas Migration in Offshore Wells: The Performance of Lead Cements

Cited by 6 publications

References 7 publications

Durability of lightweight oil-well geopolymer system in sulfate environment

Durability of lightweight oil-well geopolymer system in sulfate environment

Evaluation of Precompletion Annular Gas Leaks in a Marcellus Lateral

Evaluation of Zonal Isolation Material for Low Temperature Shallow Gas Zone Application

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