Simulation Study on Reservoir Stimulation of Multihorizontal Wells for Gas Hydrate Production in Low-Permeability Reservoirs.

The feasibility of hydrate exploitation technology has been verified by two rounds of trial productions in the South China Sea, but it is also faced with the problem of low gas production efficiency. Therefore, this paper proposed four different hydrate production cases with multihorizontal wells and established simulation models. Then, the influence patterns of reservoir stimulation and offset distances on hydrate dissociation, saturation change, and pressure distribution were studied.

Synthesis and performance evaluation of polymer-ceramic composite microcapsules as reservoir protectant for natural gas hydrate drilling.

Natural gas hydrate is a promising unconventional natural gas source due to its high energy density and huge global reserves. During exploitation, the drilling fluid may invade the hydrate formation and induce hydrate decomposition, causing reservoir damage. Herein, a novel reservoir protectant made by bio-degradable temporary plugging material (BDTPM) was developed in the form of polymer-ceramic composite microcapsules.

Design and Experimental Study of an Improved Pressure Core Sampler for Marine Gas Hydrates.

A pressure core sampler (PCS) is considered an effective tool to retrieve marine gas hydrate cores from hydrate-bearing sediments. However, according to the sampling application statistics, the success rate of pressure coring changed from 30% to 85% in different drilling wells. Such severe fluctuation will cause huge uncertainty in the practical application of technology and economic benefits.

Fabrication and property evaluation of calcium-oxide-loaded microcapsules during supplemental heat-based exploitation of natural gas hydrates.

The exploitation of natural gas hydrates (NGHs) by traditional methods is far lower than the commercial target. Calcium oxide (CaO)-based supplemental heat combined with depressurization is a novel method for effectively exploiting NGHs. In this study, we propose an supplemental heat method with the sustained-release CaO-loaded microcapsules coated with polysaccharide film.

Microstructure and Corrosive Wear Properties of CoCrFeNiMn High-Entropy Alloy Coatings.

In order to improve the wear resistance of offshore drilling equipment, CoCrFeNiMn high-entropy alloy coatings were prepared by cold spraying (CS) and high-speed oxygen fuel spraying (HVOF), and the coatings were subjected to vacuum heat treatment at different temperatures (500 °C, 700 °C and 900 °C). The friction and wear experiments of the coatings before and after vacuum heat treatment were carried out in simulated seawater drilling fluid. The results show that CoCrFeNiMn high-entropy alloy coatings prepared by CS and HVOF have dense structure and bond well with the substrate.

Corrosion and Wear Behavior of WC-10Co4Cr Coating under Saturated Salt Drilling Fluid.

Coating on the surface is one of the main ways to improve the corrosion resistance and wear resistance of materials. In this work, the corrosion, erosion, and wear resistance of WC-10Co4Cr coating and 27CrMoV substrate were compared by simulating the actual working conditions of the drill pipe. The simulation results show that the most serious corrosion occurred at the pipe body and the dominating erosion arose at the pipe joint closing to the inlet of the flow field.