Simulation study on inhibition performance of hydrate cellulose kinetic inhibitors for drilling in marine gas-bearing formations

Abstract

In the marine high-pressure low-temperature environment, it is difficult to regulate the low-temperature rheology of the drilling fluid, and the spilled natural gas is easy to generate solid gas hydrate in the wellbore, causing problems such as wellbore blockage and increasing the risk of safe drilling operations. Although there are many researches on the invasion process of drilling fluid and the development of new hydrate inhibition, there is still a lack of research on the inhibition system suitable for drilling fluid. Therefore, this paper uses the self-developed hydrate formation evaluation experimental device to simulate and analyze the effect of inhibitors in reservoir environment and optimize the scheme of drilling fluid inhibition system. The results show that: (1) Through the improvement of the experimental device of water bath methane hydrate (MH) evaluation, the accuracy and parallel control of the equipment are enhanced, and the methane hydrate formed by sea water (SW) is less than that of distilled water (DW), and the structure of methane hydrate formed by distilled water is more compact. (2) Through the evaluation experiment of single inhibitor A3, PAC and CMC inhibition system, it was found that A3 had the best inhibition effect, and when the inhibitor concentration was 1.5 wt%, it had the best inhibition effect. (3) The influence of clay types on the formation of methane hydrate is also significantly different. Bentonite soil Red (BSR) has better inhibition performance than Bentonite soil Yellow (BSY), and its ' hut ' structure formed at low temperature is the reason for the formation of methane hydrate. (4) The inhibition ability of A3 inhibitor in BSY system and BSR system solution in general, the addition of KCl can play a strong synergistic inhibition ability with A3 in BSR system, and its electric field reduces the activation energy of water molecules as well as the consumption of free water is the reason to reduce the generation of methane hydrate.

Keywords

• Methane hydrate
• Inhibitor
• Clay type
• Performance optimization
• Spatial structure