Research On Hydrate Deposition Laws And Prevention Measures Under Deepwater Gas Well Operation

The focus of oil and gas resources development has shifted from land to sea,and the exploration and development of marine oil and gas resources have shifted from shallow water to deep water,and the efficient and stable development of deep-sea oil and gas resources is of great significance to national energy security.In the production process of deep water gas wells,deepwater gas wells operations in the wellbore are often required.Deepwater gas wells operations are unscheduled operations due to downhole failures or well management needs,and are often performed using wireline and continuous tubing.Deepwater gas wells are in a complex low-temperature,high-pressure deepwater environment,and a high-temperature,highpressure formation environment.The lowering of deepwater gas wells operation tools can break the original flow state,disturb the temperature and pressure in the deepwater gas wellbore,promote hydrate generation and deposition on the inner wall of the wellbore,and even block the wellbore,which can seriously affect field construction operations.The temperature-pressure coupling prediction model was developed based on the structural characteristics of deepwater gas wellbore divided into seawater section and stratigraphic section,and the wellbore temperature pressure data were calculated by combining the field data.The longitudinal profile of wellbore temperature-pressure was plotted for gas well production,depth of deepwater gas wells tool lowering,size of deepwater gas wells tool and speed of deepwater gas wells tool lowering,and the wellbore temperature-pressure disturbance laws under deepwater gas wells operation was summarized.Based on the previous studies,the fluid flow laws in the wellbore of deepwater gas wells under deepwater gas wells operation is known to be annular mist flow,and the hydrate deposition characteristics of the wellbore are analyzed.Indoor physical simulation experiments of hydrate generation and deposition were conducted to simulate the actual working conditions of the intervention operation in the field,and the experimental results were verified with the numerical model.Indoor hydrate inhibitor screening experiments were conducted for different types of hydrate inhibitors,and MEG was selected as the hydrate inhibitor for the intervention operation by using constant pressure measurement.Based on the results of the previous study,we carried out experimental research on the selection of hydrate inhibitor injection parameters,analyzed the influence of MEG inhibitor injection quantity,injection speed and injection concentration on hydrate blockage in combination with the deepwater gas wells operation conditions,introduced the concept of safe operation time window,compared the safe operation time before and after the injection of the inhibitor to evaluate the inhibition effect,and ensured the normal operation of deepwater gas wells operation.This study can provide a comprehensive solution for the prevention and control of hydrate blockage under the deepwater gas wells operation.This study can provide a reference for the prediction and prevention of hydrate deposition under the deepwater gas wells operation.