The Thermal Stress Compensator Design And Research

In heavy oil thermal injection in thermal recovery Wells, the existence of thermal stress greatly reduces the service life of the casing can be said to be at present is a difficult problem in construction of thermal recovery, and the thermal stress is difficult to compensate means that it is difficult to eliminate safety concerns, the in the engineering of safety first, it is absolutely not allowed to exist. According to the research of the mechanism of casing damage and a large number of physical experiment and theoretical calculation, it is concluded that when the thermal recovery are excessive axial thermal stress is one of the main reason of casing damage, according to this conclusion, we consider a kind of effective way of methods or devices to solve this problem. This paper fully research the domestic and foreign research status quo of the thermal stress compensator, refer to their advantages and disadvantages, according to process characteristics to optimize design. Of tools introduced in the paper is based on the above research and development under the background of the new design of thermal ring key type thermal stress compensator, the thermal stress of the tool compensation structure can effectively solve for tubing, casing, and tree in the thermal stress, which occurs when heat is effectively extend the service life of casing string, which can alleviate this engineering problem well.In this paper, based on the investigation of a large number of data at home and abroad, integrated domestic and foreign existing theory and the specific situation of cementing operation, using as much as possible and live close to the data as reference basis, also reference in the design of the heavy oil thermal recovery well cementing operation procedures, as well as the mechanical design standard, for the device is one of the parts were analyzed, painting, simulation, through the finite element analysis software is calculated repeatedly, eventually become the ideal design train of thought, and draw out the device part drawing of each part and the whole assembly drawing. Designed a new type of thermal stress compensation devices targeted, operability and reliability, should be able to very good used in the thermal recovery of heavy oil thermal injection.Heavy oil wells, the compensator mining in the heat of steam injection, the service life of high temperature on the had a very bad effect, the nipple is extremely weak link on the casing. Due to the casing to withstand high temperature in the process of steam stimulation load, axial load, radial load and threaded constraints between parts, casing thermal expansion will not be able to stretch and shrink freely, compensator mainly depends on the contact pressure of screw thread to realize the connection. Process of steam injection, the temperature change caused the change of the contact pressure between thread, when the steam pressure or inside the wellbore fluid pressure is lower than the contact pressure between the screw thread, joint sealing will not be able to guarantee. At the same time, in the wellbore temperature falls, can produce certain residual stress on the nipple, with the increase of amount of steam injection cycle, the residual stress will gradually accumulate, until the nipple is pulled. So should design a scalable thermal stress compensation structure to avoid casing collapse. Now has developed a variety of thermal stress compensator at home and abroad, the main corrugated type, pin shear type, lock claw type, and the latest thermal material type, by applying, thermal compensation apparatus has a better function of thermal stress and stability. But the conventional thermal heat stress compensator is complicated in the structure, realizing the function of the thermal stress compensation too mechanical action, make the effect of the application.For this, this paper designed a simple structure, simple mechanical action, functional outstanding new thermal heat stress compensator, through the expansion of the heat sensitive material and inner and outer cylinder under thermal stress produced by displacement can achieve ring keys to unlock realize thermal stress compensation. Using ABAQUS finite element method, analysis of the mechanical properties of compensator under load conditions, the intensity, the compensator are repeated simulation calculations to finally determine the rationality of the size, finished7inch casing thermal stress compensator design. Designed thermal stress compensator is1760mm long and maximum overall diameter of214mm, inner diameter of157mm, comply with relevant national standards and construction conditions. The compensator by inner tube, outer cylinder cap, outer barrel, key rings, type O sealing ring (8), the inner cylinder, cylinder, heat-sensitive materials, piston, cylinder cap, buckle, collar12parts, metal materials for P-110steel grade, heat sensitive for olefin and paraffin wax mixtures, for the rubber seal ring material.After completion of the compensator design has carried on the careful analysis of the experimental design, the main consideration in actual working condition and down style may be due to friction is too large when the axial pressure, this situation may cause machine enclosed activation and failure in advance, so the compressive strength of the thermal stress design verification experiment. For under the condition of high temperature can ensure underground thermal stress compensator automatically unlock, the high temperature thermal stress compensator unlock experiment was designed for practical provide reliable inspection tools. In the numerical simulation of the design of the whole device for drilling and mechanical knowledge is a comprehensive promotion and inspection process, at the same time, design tool word has certain feasibility in theory, eventually to be inspection and practice in actual working condition.