HT-MWD Construction Report Of High Density Well
By the end of 2012, our company carried out a high density well construction in Langzhong, Sichuan province.The construct borehole of 303 well is 215.9m,design depth 4754m,vertical depth 4443m,KOP 3770m,design mud density 2.25g/cm3,high density mud increased the difficulty of the pulse signal transmission, the drilling crew using turbodrill in order to obtain high pump pressure to improve the rate of penetration, because 303 well has high pressure and high density,increase the operation difficulty ,The tools face great challenges.
二.The usage of instruments
1.Tools run in hole at 04:00 on 30th November 2012, run in hole depth is 3545m,mud density 1.70/cm3,the tools pull out from the well at 12:30 on 27th January 2013 with the depth of 4228m,and the highest mud density 2.35g/cm3,total using time 1133.5 hours.
2.After the down-hole tools pull out of the well, the pulse、probe and spare parts all with good condition after test.
3.The down-hole tools working well with mud density 2.35g/cm3,the tools is unaffected with fast transmission and low failure rate.dynamic inclination and Azimuth can satisfy the operation requirements.
4.Tools run 10 trips from the depth 3545m to 4228m,the total operation time are 1133.5 hours.ensure the smooth progress of the operation.
5.MWD's indicators were significantly greater than other MWDS system, obtain first party's approval,save lots of drilling time.
According to the operating characteristics of MWD,control the parameters of the drilling process, then according to the selected type of drill tool,tool size, bit port size, density of the mud, plastic viscosity and pump displacement, through the calculation of WINPUL software,reasonable choice for orifice, stator and impeller to ensuring the pulse signal while reducing equipment abrasion and stress erosion of poppet..
Yuan lu 303 instrument matching list as follows: 1.800' orifice,1.520' poppet, 35°impeller and 27° stator, the pulse generator speed reached to 2600RPM in the actual operation, the pulse signal amplitude was 100 psi, although the two parameters were lower than the theoretical calculation values, but the equipment working properly,data provided by the tools completely meet the requirements of operation, the total operation time were 1133.5 hours with trouble free and uncorroded.
2.The selection of control parameters
The pulse of MWD 650 width are: 0.5 S, 0.6 S, 0.8 S, 1.0 S, 2.0 S. The basis for selecting the pulse width are pulse signal intensity, pulse working time and directional engineer's requires
When conventional pulse width select as 0.5S,the tool face update time is 9 seconds, When conventional pulse select as 0.8S, the tool face update time is 11 seconds, obviously selecting pulse width as 0.5S can favor the directional construction. furthermore that the well depth is close to 4000 meters, the pulse width select as 0.5S absolutely faster than 0.8S of the transmission frequency,but the pulse signal will be smaller, considering the signal transmission attenuation and high mud density, the pulse signal would be very poor. According to the requirements of the pulse maintenance (200-300 hours), in order to reduce pulser abrasion and extended the usage of the tools, at Yuanlu 303 well, all instrument pulse width were set as 0.8S, the amplitude of the signal range between 80-100PSI.
四.Instrument Operating Requirement
1.In the construction process of 650 MWDS system must ensure that the pump in good condition, the air bag inflated enough ( 40%-50% pressure of the stand pipe in normal ) and pump pressure stability, ensure that won't make big noise.If there is something wrong with the pump, should be fixed immediately.
2.In order to detect the data needed for operation after open the pump,in addition to the special requirements in the process of open the pump,shall not stop the pump in 2 minutes,the pump strokes should be reached in normal within 30 seconds.pump pressure stable in 50 seconds,so that we can get the data in 2 minutes and greatly improve the work efficiency.otherwise the instrument can’t detect the signal immediately,it’s necessary to restart the pump or using lots of time to try different stroke parameter,the survey efficiency is very low.
3.Ban switch pump for many times rapidly,repeatedly switch pump can cause impact to the rubber,easy to cause the rubber burst.
4.Connect the kelly bar with pump open to do the shallow test.the pump open time shall not be less than 3 minutes,and inject the mud with normal drilling pump stroke speed.after passing the shallow test.should waiting for MWD engineer's notification to start run in hole.the speed control in 15 stand / hour, inject mud every 20 stand until filling.
5.Every time start pumping must be put the drilling pipe filter in place, if connection, should put the filter in the drilling pipe which under the the kelly bar, if trip up,should get the drill pipe filter out.Ensure that the filter in the drilling pipe keep clean without sundry.No longer use drill pipe filter should be cleaned.
6.In the construction process,in order to ensure the MWD tools effective working time and performance, requires to use desander, desilter and centrifuge, make sure the mud sand content is not higher than 1%.
五、Advantages of HT-MWD in high density well
HT-MWD 650 has high reliability,variety of instruments combination, easy installation, low failure rate.We ensure that every string equipment before sent to rigsite should pass strict test . The pulser structure of HT-MWD design is not the double valve,through the reciprocating movement of the plunger inside the pulser to inject oil, generate high pressure in the confined space, drive the lifting rod which connected to the poppet to generate piston movement, and then work with the orifice to produce the pulse signal.This design overcome the defect which include easy plugging and easy erosion of double valve structure, applicable to variety of mud system.