Development and Evaluation of Insulation Materials for Deepwater Cementing.

Marine oil and gas resources are abundant in deepwater regions, where the shallow seabed harbors natural gas hydrate layers due to the cold temperature and high-pressure environment. Hydrates are prone to thermal decomposition, which can compromise the integrity of cement sealing and even lead to accidents like blowouts. While current low-hydrated heat cement systems mitigate hydrate decomposition from cement hydration heat during the waiting period for cementing, they do not address heat transfer from deep strata to shallow hydrate layers through fluid circulation in the tubing during deep oil and gas development.

Investigating the applicability of novel hydrate dissociation inhibitors in oilwell cement through molecular simulations.

In the field of hydrate formation cementing, the method of developing the low hydration exothermic cement systems cannot effectively solve the problem of hydrate dissociation caused by the hydration heat release of cement. Therefore, we proposed a new approach to address this issue by employing cement additives that can effectively delay the dissociation of hydrate. In our previous work, we designed a novel hydrate dissociation inhibitor, PVCap/dmapma, however, its applicability with cement slurry remains unverified.

Laws of Hydration Heat of Cement and Hydrate Stabilization in Shallow Formations of Deep Seawater.

When cementing is required in marine deepwater hydrate formations, the heat released from the hydration process of oil well cement can easily lead to hydrate decomposition. It is necessary to clarify the initial phase transition temperature of the hydrate layer under the influence of cement waiting for setting so that it can meet the stability of the hydrate layer during cementing. In this paper, based on the actual conditions of offshore deepwater cementing, the coupled temperature field model of cement sheath hydration heat source-well wall hydrate decomposition is established by considering the hydration heat release during the cement waiting process and the phase change heat absorption of the well wall hydrate.

An experimental study of the correlation between P-wave velocity and the physical properties of weakly cemented formations.

Deep water and shallow layers mostly feature weakly cemented formations, with complex geological structures, geological looseness, susceptibility to collapse. In order to obtain information on weakly cemented formation materials, weakly cemented argillaceous siltstone is simulated as the research object and the focus is on analysing the influence of ultrasonic frequency, density, particle size (porosity), and compressive strength on P-wave velocity and establishing the correlation relationship between longitudinal wave velocity and each parameter through indoor simulation experiments. The results showed that there is a linear relationship between P-wave velocity and ultrasonic frequency in terms of positive correlation as well as compressive strength.

Preparation and Characteristics of a pH Intelligent Response Blocking Agent for the Microcrack in the Cement Sheath.

Microcracks in the annular cement sheath of oil wells frequently cause annular water channeling. Traditional cement squeeze technology has a low success rate in controlling this issue. Based on the conventional profile control water-blocking agent for underground in situ gelling and polyacrylic acid, a pH intelligent response microcrack-blocking agent was developed to block the microcrack in the cement sheath.

Preparation and performance evaluation of non-foaming styrene-acrylic latex for cementing slurry.

The latex used conventionally for oil-well cementing can lead to serious foaming issues in the cement slurry, which not only affects the accurate measurement of the density of the latex-containing cement slurry, but also is detrimental to cementing construction. A large amount of a foam stabilizer used for latex preparation is mainly responsible for foaming of the latex-containing cement slurry. In this study, soap-free emulsion polymerization was conducted using 2-acrylamido-2-methylpropanesulfonic acid (AMPS), styrene (St), and butyl acrylate (BA) as the reaction monomers and the effects of the AMPS dosage, monomer ratio, reaction temperature and stirring speed on the performance of the latex were investigated.

Effects of microstructure on compressive strength of silica sand-enhanced oil well cement at a wide temperature range.

The influence of microstructure of silica-enhanced cement on the mechanical performance of cement is difficult to describe. In this study, we used the scanning electron microscope and image processing method to investigate the relationship between the complicity of cement microstructure and compressive strength under various temperatures and curing times. Fractal dimension was applied to describe the complicity of silica-enhanced cement.

A novel hydrophobically associating water-soluble polymer used as constant rheology agent for cement slurry.

During the process of well cementing in deep water, the cement slurry experiences a wide range of temperature variation from low temperature at seabed to high temperature in downhole. The elevated temperature affects the rheology of cement slurry. The change of rheology of cement slurry could influence the safety of cementing operation.

Adsorption mechanism of Pb in montmorillonite nanopore under various temperatures and concentrations.

Adsorption of lead (Pb) onto the montmorillonite (Mt) surface is one of the key approaches to remove Pb in geological and environmental engineering. Temperature and initial Pb concentration are two essential factors that influence the adsorption capacity of Mt on absorbing Pb. However, the nanoscale governing mechanism of temperature and initial concentration on Pb adsorbing of Mt is still unclear.

Utilization of metakaolin-based geopolymer as a mud-cake solidification agent to enhance the bonding strength of oil well cement-formation interface.

This research work designed a novel mud-cake solidification method to improve the zonal isolation of oil and gas wells. The calculation methodology of mud-cake compressive strength was proposed. The optimal formula of activator and solid precursors, the proper activating time and the best activator concentration were determined by the compressive strength test.

Bentonite-Acrylamide Hydrogels Prepared by the Nonmixing Method: Characterization and Properties.

A significant amount of research has been conducted on bentonite-acrylamide hydrogels. These gels are usually prepared by uniformly mixing bentonite with reactive monomers. Herein, a new preparation method of bentonite-acrylamide hydrogels has been proposed to cater to one novel application of bentonite-acrylamide hydrogels.

Effect of carboxylic group on the compatibility with retarder and the retarding side effect of the fluid loss control additive used in oil well cement.

The retarding side effect and the compatibility with other additives are the main problems that limit the field application of the synthesized fluid loss control additive (FLCA). The effect of the type and content of carboxylic acid groups on the retarding side effect of FLCA and the compatibility between FLCA and the retarder AMPS-IA synthesized using 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and itaconic acid (IA) was studied in this paper. The type and content of carboxylic acid group have a great influence on the fluid loss control ability, the compatibility with retarder and the retarding side effect of FLCA.