Method for cooperatively regulating and controlling the phase state of natural gas hydrate in reservoir through drilling fluid additive and temperature and pressure field

Abstract

The invention relates to a method for cooperatively regulating and controlling the phase state of a natural gas hydrate in a reservoir through a drilling fluid additive and a temperature and pressurefield, and belongs to the technical field of natural gas hydrate development. The method comprises the following steps of calculating dynamic distribution rules of a reservoir temperature field and anatural gas hydrate decomposition interface under the conditions of different drilling fluid displacements, injection temperatures and drilling fluid additive concentrations, and drawing a relation curve of the drilling fluid additive concentrations, the injection temperatures and the displacements with the saturation of the reservoir natural gas hydrate; and obtaining an optimal combination of drilling fluid additive concentration, injection temperature and displacement by utilizing a particle swarm algorithm, so that the saturation change of the reservoir natural gas hydrate is minimum. Accurate regulation and control of the reservoir natural gas hydrate phase state of deep-sea shallow-layer complex-structure well drilling can be achieved, and method guidance is provided for inhibiting reservoir natural gas hydrate decomposition in the drilling process.

Description

technical field [0001] The invention relates to a method for synergistically regulating the phase state of natural gas hydrate in a reservoir with a drilling fluid additive and a temperature and pressure field, and belongs to the technical field of natural gas hydrate development. Background technique [0002] Natural gas hydrate is a crystalline substance formed by natural gas and water under high pressure and low temperature conditions. The total amount of hydrate resources in the world is about twice the total amount of traditional fossil energy. The hydrate resources in my country's sea area are about 80 billion tons of oil equivalent. It is an important potential high-efficiency clean oil and gas replacement energy. In recent years, many developed countries such as the United States, Japan, and Canada have carried out research on hydrate production trials. Two rounds of trial production of deep-water natural gas hydrate in the Shenhu area of ​​the South my country Sea ha...

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Problems solved by technology

Temperature and pressure are the basic conditions for regulating the phase state of hydrates. Drilling fluid additives can change the phase state conditions of hydrates. At present, the chemical methods for drilling phase state stability in natural gas hydrate reservoirs mainly focus on the research of chemical inhibitors for hydrate formation. The chemical agents for maintaining the stability of the gas hydrate phase state in the reservoir are still in the stage of experimentation and molecular simulation optimization, while for the interaction between the drilling fluid additive and the gas hydrate reservoir, the chemical properties of the drilling fluid additive have a significant effect on the gas hydrate There are few reports on the influence mechanism of phase stability

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