Study On The Diffusion Simulation Of Leaked Oil Gas On Offshore Platforms Based On CFD

The paper describes the status quo of CFD diffusion numerical simulation ofleaked gas abroad and the basic principles of CFD, summarizes the basic methods ofgas diffusion study, innovatively proposes CFD simulation technology roadmap ofleaked oil-gas on offshore platforms in order to study the movement of leaked oil-gasand important factors of its spread on offshore platforms. Combined with theproliferation of dangerous gas leak characteristics and complexity of offshore marineplatform operating environment, important factors of the study include sea-windspeed and direction, leaked angle and platform layout.Through the latest analysis of wind conditions in Bohai Bay, the initial values ofthe wind direction and speed are chosen. Leaked angles are classified according toactual situations. The models of platform layout are built according to the basis ofoffshore platform layout. Execute CFD analysis of leaked oil-gas under differentcombinations of variables scene using FLUENT6.3.In the paper, the control variate method is accepted to analyze simulation results.Simulation results species include velocity contour, pressure contour, component riskzone, oil-gas pathlines. Under the environmental conditions of Bohai Bay, the riskarea quantization table of the four areas in each combination is summed up throughextracting C3H8and C4H10explosion hazard area. Execute comprehensive andsystematic study on the diffusion law of leaked oil-gas on offshore platforms.The results show that: Sea-wind speed and direction, leak direction, platformlayout will largely affect the diffusion of leaked oil-gas.Impact research of platform layout shows that:C3H8risk zone is much smaller than that of C4H10, the two regions share similar edges. Ascending the risk areas, platform layouts are inverted S-type, one-type,mouth-type, L-type. The inverted S-shaped layout is summed up to be the best.Impact research of sea-wind speed shows that:(1) Within a sea-wind speed range, as the wind speed increases, the dangerouszone expands meaning that quick wind speed favors the diffusion of oil-gas leaks.Area quantify figures of four areas show that the percentages of the area at risk owndifferent abnormal demarcation points in living area, power and storage areas, and asthe wind speed increases, the rest decreases;Although the same presence of abnormalpoint in production area, the rest increases with the increase of wind speed.(2) The main changes of velocity contours occurs in storage area. With theincrease of the sea-wind speed, the speed maximum of leakage field shows adownward trend.(3) The main changes of pressure contours occurs in production area. With theincrease of wind speed, maximum pressure decreases with an abnormal demarcationpoint in sea-wind5.7m/s; absolute value of the minimum pressure increases with acut-off point in sea-wind3.6m/s.Impact research of sea-wind direction shows that:(1) With the counterclockwise rotation of the sea-wind, total danger-zone areaexpands. the total hazardous area of two components in power area has risen, and theremaining three districts ratio decreases.(2) The main changes of velocity contours occurs in production area. Under thecertain sea-wind speed, sea-wind direction changes have little effects on the diffusionfield.(3) The main changes of pressure contours occurs in production and power areas.Under the certain sea-wind speed, sea-wind direction changes have little effects onthe pressure maximum in the diffusion field,while mainly affect the distribution oflow pressure field.Impact research of leaked direction shows that:(1) C3H8:From0degree to30degrees, the leaked risk area increases as the angleincreases; From30degrees to60degrees, the total area at risk decreases as the angle increases; From60degrees to90degrees, the total area at risk increases. Angularinterval of trends is30degrees.C4H10:As leaked angle increases, the risk area shows a decreasing trend afterthe first increase with a demarcation point in the direction of disclosure30degrees.(2) In the leaked direction60degrees,75degrees,90degrees, three velocitydistributions are similar, and three pressure distributions are similar.Maximumpressure shares the same trend with maximum velocity.According to the diffusion study on important factors of leaked oil-gas onoffshore platforms, more realistic offshore contingency plan is developed.The research can provide a reference for oil-gas leaks studies on offshoreplatforms as well as a basis for the development of emergency response plans, andmake contributions in order to improve the national security of oil-gas explorationindustry.