Abstract: With rapid increasing in exploration workload and increasing in drilling depth,a series of major technical problems occurred when drilling deep,HPHT,low porosity and low permeability reservoirs.In view of these problems,the drilling technology and process are analyzed in this paper,including casing program optimization of complicated pressure system,establishing low free water drilling fluid system with excellent protection ability and borehole stability,cementing techniques for gas-channeling prevention in high pressure,low porosity and low penneability reservoirs,drilling technology for increasing ROP in different sections.The application results indicate that these techniques are very useful to solve the drilling problems,protect reservoirs.By using these techniques,the operating efficiency has been improved greatly,and the requirements for deliverability test can be reached.In order to meet the requirements for drilling engineering and reservoir protection in horizontal well of oil field EP24-2,a solid-free rapid weak gelling drilling fluid was developed by experiment.The drilling fluid has high yield point to plastic viscosity and high low-shear rate viscosity(LSRV),and can be used to solve the problems of carrying cutting and cutting bed in horizontal well.The lab evaluation tests indicated that the drilling fluid has excellent inhibiting ability and lubricity,less filter loss,with capability to resist temperature and pollution,being capable of borehole cleaning and reservoir protection.In view of the technology of open hole completion in horizontal well of oil field EP24-2,study has been conducted on the gel breaking capability of gel breaker JPC to drilling fluid and its filter cake.The results indicated that gel breaker JPC could degrade effectively polymers and avoid reservoir pollution by polymers.The results showed that the drilling fluid had unique rheology,and its maintenance is simple.In addition,it had excellent capability for reservoir protection,being degradable,suitable for drilling the horizontal sections in horizontal well of the oil field EP24-2.During operation of XX adjustment well in a oil and gas field of East China Sea,after drilling to the depth of design,it is decided to continue drilling to explore oil and gas bearing conditions of deeper formation.During drilling process,overflow occurred when drilling to 5 108 m.When killing the well,drill pipe piercement occurred at 731 m,resulting in short circulation.When displacement killing method was applied,circulation loss and choke line piercement occurred,which lead to further complications with insufficient pressure level of equipment.After a series of unconventional well kill techniques,killing well is successful.It is a successful case of well killing.Qingdong Block is located in northern faulted zone,Qingdong sag in Jiyang Depression.The geologic structures are complex in Shahejie Formation,faults are well developed locally,and ground stress is clear below the faults.The mudstones in Sha-3Member are hard and crisp,and lamination is clear.The borehole was very instable during well drilling,and complex accidents occurred frequently.Repeating dummy trips occurred frequently,and stick was severe case,which slow down the exploration progress in the study area severely.By using aluminum-amino inhibitive,sealing and anti-caving drilling fluid,many measures were taken,such as suitable density supporting,multi-variate synergism inhibition,compelling formation sealing,and reasonable rheological behavior controlling.In addition,corresponding onsite maintenance technology was taken,which guaranteed the borehole stability of Well Qingdonggu-1 in Shahejie Formation.Well Qingdonggu-1 was completed in advance,and borehole was stable in Shahejie formation.In addition,the drilling period was shorten by 20%.With the increasing in life of platform service,the environmental conditions for platform service become disadvantage due to the change in sea conditions in Bohai Sea.It is proposed that in Bohai Sea,the environmental condition for offshore platform structure design should be 100 year return period rather than 50 year return period.Through comparison analysis on the 50 year/100 year return period environmental condition for structure design of partial center platform and wellhead platform in the Bohai Sea,it is proposed that 100 year return period should be used to replace 50 year return period in the offshore platform structure design in Bohai Sea.Cantilever beam load test is one of the most important methods for jackup rig before putting into service.In this paper,with 200 feet jackup rig "Offshore Oil 923" as an example,the method of cantilever beam load test has been discussed.The results proved that this method is effective,safe and easy to operate,which can provide valuable experience and reference for other engineering projects.