Influence of cement top on wellhead uplift height of deepwater high temperature and high pressure well

During the oil and gas production of deepwater high temperature and high pressure well, the oil and gas flow carries the bottom heat to the wellhead, leading to thermal elongation of free casing and then wellhead uplift, and thus there is failure risk of device seal at the wellhead. In this paper, a model for calculating the wellhead uplift height in the oil and gas production stage of deepwater high temperature and high pressure well was established. Then, the simulation experiments of wellhead uplift under the conditions of double-layer string with different cement tops and multi-layer string coupling cementing were carried out based on the independently developed simulation experimental device of wellhead uplift of high temperature and high pressure well. It is shown that the elongation of each layer of string under the working condition of double-layer string with 100% cement top is much smaller than that under the working condition with 50% cement top, and the maximum elongation of each string under the working condition of multi-layer string coupling cementing is also greatly smaller than that in the working condition without cementing. It is indicated that cementing has a certain binding effect on wellhead uplift. The simulation experiment verifies that the error between the calculation result obtained by the established model and the experimental data is less than 10%, so the model can be used to predict wellhead uplift height under different working conditions and provide a technical reference for the scientific design of wellhead uplift prevention measures.