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VYM - Well Control Project.vym Tue Jun 2 2 Hydrostatic pressure of see water is not affected by oil and gas plums Assumptions blowout similator developed by FORTRAN to model blowout rate and dynamic kill technique using a relief well Santos, 2001 During the blowout the water bouyancy can be afected by oil and gas plums Adams et al., 2003 A comprehensive hazard and operabilty analysis, including risk assessment Lage et al.2006 A blowout similator has been developed and validated with filed experiences from a North Sea fas field Approprite use of hydraulic roughness to estimate the blowout rate Oudeman (2007,2010) Wellbore stability issues during blow out Willson 2012; Wilson and Sharma, 2013 Well control contingency planning Morrell et al.,2013 Blowflow used Bayesian approach to evaluate the probabilty distribution of potential blowout rates and volumes Arild et al., 2008 Karlsen and Ford,2014 Literature reviwe OLGA was used Samples of weels needed to be altered to meet WCD dynamic blowout rate wellbore flowing temperature Well design Simulation The daily rate of an uncontrolled flow at the see floor with a hydrostatic water column or atmospheric pressure at see level if well is on an existing platform Should include all hydrocarbon-bearing zones unobstructed casing and liner no drill pipe in the hole uncontrolled flow Worst case Discharge scenario(WCD) a dramatic increas in ultradeep water drilling in Gulf of Mexico 1000 feet 5000 feet deep water and ultra deep water drilling definition Introduction Regulatory agency requiers the submission of a worst discharge analysis in order to get the permit to drill in the US offshore fileds increased rictional pressure losses in kill lines formation fracture strength deep water blow out control case is more challenging Required Pump capacity burst pressure of the formation limits Operational parameters optimization to evaluate the operational parameters durimg kill process dynamic stimulation of multiphaseflow are carried out frictional pressure loses U-tube effect FLuid density variation kill mud density pump flow rate pump down staging releif well drill string and trajectory optimization of operational sequence The stimulation account for reuired pumpt capacity reqired volume of the kill mud optimal flow rate arrangement minimum time reqired to get full kill mud return to the see floor during the well kill operation The paper shows Advanced transient software model were used Abstract Vertical well in Gulf of Mexico See water depth 6000 ft~1820 m Water temp=40 F~4.4 C six reservoir layer volatile oil production TVD=32000-33000 ft ~9700-10000 m P_reservoir=24000 psi~1633 atm T_p=230 F~110 C GOR=1300 scf/bbl end of Day 1 wellbore flowing bottom hole pressure=18000 psi~1225 atm oil rate=237000 bbl/day Gas rate=308 MMscf/day OLGA simulation result for WCB Target well Description Similar to target well Open hole section=100 ft 8.5 in to reduce frictiononal losses in the annulus Bottom of 6 5/8" drillpipe was pulled back to the top the 10 1/2" there are two 4 1/2 " kill lines for the relief well Releif well description INTRODUCTION 6 5/8" & 5" in relief well 10390 bbls 1703 ppg mud used blowout successfully controled without exceeding the operational window It takes 150 minutes to kill the well after inception Results of Bloeout control intersection depth is 100 ft blow the last casing show depth avoid drilling into reservoir zone target well can be found by magnetic ranging tech at depth 30100 ft TVD lower inimum mud density high pump pressure high equivalent circulation density in borehole section resluts more frictional pressure loss in the annulus tends to have longer open hole section deeper intersection point Intersection point heat losses to the surronding transient thermal effect must include Joule-Thomson effects transient thermal behavoir in the rock around the wellbore heat transfer to the casing and its fluids transient thermal effect must include dynamic temperature effects must be considered pripor to WCD temp=close to geothermal gradient a transient simulator shall be used to predict the temperature variation during WCD A steady state simulator would predict the steady state temp profile which is valid during WCD All of the following predictaion were done by the transient simulator OLGA Target Wellbore Temperature Change during Blowout partly is good since can help the target well by reducing the pump pressure The fluid in the relief well will be sucked into the blow out well due to the strong differences of Pressure It is important not to intersect until all the mud pumps and kill fluids are lined up and ready U-Tube effect during blow out well control high enough to maintain the static balance in the blow out well required minimum kill mud density maybe higher than the formation fracture pressure gradient Fracture pressure gradient of 16.04 ppg 15.8< kill mud weight <17.92 , in the simulation=17.0 ppg In static condition, after the target well is filled up with the 17.0 ppg kill mud to the sea floor, the equivalent mud weight is 15.3 ppg at the depth of weakest formation. The higher mud density, the less volume and time required, but the more difficult to get the kill mud prepared the bottom o 6 5/8" drillpipe was pulled back to the top of 10 1/2" tieback to reduce frictional losses in the annulus, before kill operation , the bottom of the drillstring was pulled back to the casing section the pump pressure capacity is 8000 psi kill mud density=17.0 ppg minimum pump rate 3700 gpm to kill the blow out Optimize kill Mud Density CONSIDERATIONS due to the very high flow rate of the reservoir fluid and gas expansion the scenario with the riser attached may be worse thatn the WCD scenario without riser scenarios with and without riser are studied density of the reservoir fluid is less than the density of see water In hydrodynamics, a plume is a column of one fluid moving through another. Several effects control the motion of the fluid, including momentum (inertia), diffusion and buoyancy (density differences). Pure jets and pure plumes define flows that are driven entirely by momentum and buoyancy effects, respectively. Plume: is the time that blowout starts to occur and blowout rate reaches steady state. Once unloading period ends, kill mud is pumped to the relief well to kill the blowout Unloading period Is a process in which the relief well is drilled near to the target well and continues to pass it to provide an azimuth change from relief to target well. Pass-By: Magnetic ranging technology can be classified as either "active" systems, which generate the necessary magnetic field, or "passive" systems, which rely on the remnant magnetic field of the steel in the target wellbore. Magnetic ranging tech POINTS & definitions the transient thermal model shows that the maximum wellbore flowing temperature is much higher than that of formation temperature The temperature under the blowout scenario with riser attached is higher than that of the scenario without riser attached to the wellhead At the time of seven days and top of 10 1/8Љ tieback, the wellbore temperature is 19.3 ̊F higher than the reservoir temperature, 126.3 ̊F higher than the formation temperature at the same well depth on temperature The frictional pressure losses from kill lines, low clearance annulus and borehole section can make the blowout kill operations exceed the pump capacity and formation strength pumping down the drillstring and annulus simultaneously repositioning drillstring changing BHA configurations Neutralized strategy on frictional pressure U-tube effect during the blowout kill can help reduce the pump pressure. With small pump rate pump pressure can be almost zero because the falling rate in the relief well is higher than the pump rate. U-Tube effect pump rate stage down can help blowout kill stay in the operational window when the pump pressure approaches pump capacity and the annulus pressure to the fracture pressure of formation On the pump pressure helps simulate the blowout kill in various scenarios optimize the operation parameters to ensure that well control can be re-established in case of an ultra-deep water worst blowout scenario more reasonable scientific bachground to solve the problem transient simulator advantages Conclusions gas breaks out at 10000 TVD ft without riser higher mixture velocity with riser gas breaks out at 16000 TVD ft with riser mixture velocity vs Depth with/out riser at the time of 24 hours Fig 3. & Fig4. wellbore flowing temperature vs Measured depth without riser at various times from 1 hout to 7 dayes the wellbore temp is increasing The temp at 14 days is almost the same as that at 7 days maximum temp 244.5 F seen at 18000 ft on the top of 10 1/8" tieback max temp is 121.5 F higher that formaton temp and 123.5 F at the same well depth Fig5. wellbore flowing temperature vs Measured depth with riser at various times the reservoir fluid is follwoing to the atmospheric condition according to the outlet mixture velocity and density outlet pressure is calculated based on the heigth and desity of the fluid plume maximum temp 249.3 F seen at 18000 ft on the top of 10 1/8" tieback max temp is 121.5 F higher that formaton temp and 126.3 F at the same well depth Fig 6. the maximum temp occured at seven days in with/out riser scenario points depth vs pressure for wells wellbore and annulus pumping down drill string and annulus simultaneously repositioning drillstring Considering different BHA and Drillpipe configurations if pump pressure exceeds capacity due to hgh frrictional pressure Fig 7. Depth vs different wells wellbore,annulus,kill line pressure Relief well kill line mud level dropped to 3000 ft due to U-tube effect Fig 8. pumped volume rate vs time for releif well after the target well is field with kill mud, pump pressure is almost zero since the falling rate in the relief well is higher than the pump rate Fig 9 the amount of 10,390 bbls 17.0 ppg mud is required to successfully control the blowout Table 1. Pump Pressure vs time pump pressured controled to avoid formation breaking and pump capacity itself Fig 10. outlet gas flowrate and liquid density vs time 150 min to have kill mud return to the see floor and get the blowout well killed Fig 11 & 12. FIGURES INTERPRETATIONS WHAT HAD AUTHORS DONE?

spe-170256-ms map

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