Abstract
In this study, we investigated the effect of compression on the micromechanical and the petro- physical properties of salted wellbore cement systems. The experiments were conducted using a customized bench scale model, which utilized an expandable tubulars simulating the compression of a previously cemented casing under field-like conditions. The “mini-wellbore model” sample consisted of a pipe inside pipe assembly with a cemented annulus. The cement samples were cured in a water bath for 28 days prior to the compression experiments to allow adequate hydration. The impact of compression on the cement’s petro-physical and mechanical properties was quantified by measuring the porosity, permeability and hardness of salt cement cores drilled parallel to the orientation of the pipe from the compacted cement sheath. Permeability (Core-flood) experiments were conducted at 21℃, 10,342 kPa confining pressure for a period of 120 minutes. During the core-flood experiments, conducted using Pulse-decay method, deionized water was flowed through cement cores to determine the permeability of the cores. The results obtained from these experiments confirmed that the compression of the cement positively impacted the cements ability to provide long term zonal isolation, shown by the effective reduction in porosity and permeability. Furthermore, the results confirm reduction in the detrimental effect of salt on the strength and stiffness in post-compression cement.
Highlights
Wellbore cementing which forms an integral part of well completion is important in ensuring effective zonal isolation of the well
We present our findings from an experimental determination of the impact of compression during hydraulic fracturing and the effect of pressure variation during pressure testing and hydrocarbon production on the petro physical and micro-mechanical properties of salted cement systems placed in the subsurface as an integral part of oil well construction
Based on the findings from this study, the following conclusions can be drawn: 1) The reduction in the porosity and permeability of the cement sheath after compression shows that the compression positively impacts the cements ability to prevent flow and provide adequate zonal isolation
Summary
Wellbore cementing which forms an integral part of well completion is important in ensuring effective zonal isolation of the well. Salt cement systems have proven effective in the maintenance of formation competency in shale sections and salt cement blends have been used in the field to minimize the inflow of gas into primary cement slurry column of wells in the ten section of Kern County field with severe damaging effect on the cement integrity [4]. The mechanical properties of cement such as hardness and compressive strength have been shown to be significantly affected by the amount of water present in a hydrated cement paste. Review of current literature has revealed no documented findings on the effects of oil-field operations such as hydraulic fracturing and pressure variations during casing testing and geological impacts such as formation subsidence, which results in the compression of the cement on the micro-mechanical and petro-physical properties of the cement
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
