| Substructure is an important part of drilling rig as a supporter. The main components of drilling rig, including derrick (and the equipments installed with it, such as crown block ,traveling block, hook blocks, swivel, etc.), rotary table, drawworks, power transmission equipment, and mechanization operation tools and assistant drilling equipment should be installed on the substructure, and rely on the substructure to maintain their relative position and mounting dimensions. Substructure provides relative position of main components, installation size, space for drilling strings and operation place of workers are also provided by substructure.Drilling technology requires sufficient strength, rigidity and stability of substructure to meet the security needs of drilling. The height (the height rotary table) of drilling platform that the substructure provides must meet the requirements of drilling technology to install blowout preventers and mud circulation height space. Under the premise of the above requirements, we should ensure the convenience of rig disassembly and movement, reducing non-drilling time and saving drilling costs.It is to propose a substructure type that fit for the conditions of Daqing Oil Field, lifting-type substructure which is based on the advantages and disadvantages of common type drilling rig, the factors that affect the substructure type and it's developing trend. The substructure can be fit for two different drilling platform heights which is adjusted by hydraulic cylinders. For this specific substructure type, we study and design a hydraulic system which can raise and lay down derrick overall and adjust the height of drilling platform vertically based on the whole arrangement of drilling rig and structural characteristics of the derrick and substructure. Using two tertiary companding double acting hydraulic cylinder to raise and lay down the derrick, the basic circuit adopts manually reversing, with a throttle and balance speed and other functions, to ensure stability of derrick. Using four double acting single hydraulic cylinder to adjust height of the base platform, its basic circuit uses four joint set manual selector valves and three flow distributing and collecting valves to achieve the synchronization of four hydraulic cylinders and the micro adjustment function when they are not synchronized, to ensure that the drilling platform is always horizontal during the lifting and falling process and has throttle function and one-way hydraulic locking feature. According to actual structure and stress condition of the derrick and the substructure, establish a derrick finite element analysis model of the spatial beam element and the finite element analysis model of spatial entities of the base. Considering derrick rising, maximum hook load and casing installation three most dangerous working conditions, calculate the load that the derrick putting on the substructure with the ANSYS finite element analysis software, analyze the force and deformation on each part of the substructure. And then re-design and re-calculate the weak parts of the substructure eluding excessive force and deformation to ensure the safety of the substructure.So far, this lift-style base is used more than 30 sets in the Daqing oil field, the cumulative welldrilling is more than 1,000 wells, the substructure has been proved safe, reliable, and two drilling platforms are highly adaptable, lift and lay down derrick and hydraulic system of drilling platform are of flexibility and stability, and meet the requirements of the overall haulage to improve drilling efficiency. |
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