Shingo Asamoto

Well integrity assessment for CO2 injection

Purpose – In the carbon dioxide capture and storage (CCS) project, the integrity of CO2 injection wells plays a vital role in the long‐term safety of CO2 storage. The authors aim to practically investigate possible CO2 leakage of a CO2 injection well section during the injection operation and shut‐in by the thermomechanical FEM simulation. The application of numerical simulation to the CO2 injection well deep underground is the first step that will help in the quantitative evaluation of the mechanical risks.Design/methodology/approach – The injection of CO2 at a temperature different from those of the well and the surrounding geological formation is likely to cause different thermal deformations of constitutive well materials. This could lead to cement cracking and microannuli openings at the interfaces of different materials such as casing/cement and cement/rock. In this paper, the possibility and order of magnitude of cement cracking and microannuli creation in the cross section of the well are assessed...

Cracking Risk and Regulations

This chapter is focused on the cracking risk at early ages. After general considerations about cracking, the cracking risk prediction is discussed. Two main ways to assess this risk are considered: through an evaluation of the tensile stresses and through an evaluation of the strains. Finally, the evaluation of crack opening at early ages and the reinforcement design in regulations are presented.

Hydration and Heat Development

The driving process of early-age cracking in massive element is the hydration and reactions of the binder that composes the concrete. Indeed, these reactions are highly exothermic and lead to heat generation in the structure. It is thus of primary importance to be able to characterise and predict the heat generation of binders in order to assess the early-age cracking risk of a concrete structure. The first section of this chapter presents the main physical phenomena responsible for this heat generation. It must be kept in mind that only the general phenomena of hydration are presented. The aim is only to present how the chemical reactions lead to heat development and water consumption (which are of interest for our purpose). The reactivity of binder is a large scientific subject, and more detailed review can be found on this subject in other RILEM TCs (for instance, 238-SCM). The second (and main) section of the chapter is dedicated to the modelling of the heat development induced by cement hydration. Several approaches are presented: affinity-based models (that can be easily implemented in finite element codes), microstructural models (even if they are less adapted to the massive structure modelling), data mining, or inverse analysis.

Development of New Hybrid Composite Girders

A hybrid Fiber Reinforced Polymer (FRP) bridge girder consisting of carbon fiber reinforced polymers (CFRP) and glass fiber reinforced polymers (GFRP) has been developed in Japan. A number of tensile and compressive coupon tests were conducted to determine the material properties of hybrid FRP laminates which were used in the analytical investigations of the large-scale FRP beams. A series of beams with wide flange widths varying the volume content of CFRP in flanges were tested under four-points loading. The experimental investigations revealed that the failure mode of these beams was induced by the local buckling of the compressive flange. In order to avoid the local buckling, stiffeners were installed in the flexural and shear span of beams. Although an appropriate installation of stiffeners can prevent effectively the local buckling, however the hybrid FRP beams failed prematurely due to stress concentration at the loading points. Analyses were carried out and showed a good correlation with experimental results.