气体钻井环空堵塞安全解堵压力研究

发布时间：2018-05-09 07:11

本文选题：气体钻井 + 环空堵塞　；参考：《西南石油大学》2015年硕士论文

【摘要】：在气体钻井过程中,可能因为地层产气、地层出水或施工不当等因素造成井壁失稳从而导致环空堵塞,堵塞后由于注气或产气引起环空压力集聚。当压力集聚一定程度后,高压气体冲破岩屑堵塞段形成高速气流并携带岩屑流动到井口,对井口造成冲击和冲蚀。因此为确保井口的安全,需要获知此类情况井口受到的冲击力和冲蚀速度。本文针对气体钻井的这种特殊工况下的安全问题展开了以下研究并取得了一定的认识： (1)将地层渗流模型、产气模型、状态方程以及达西公式耦合,建立了井底压力的计算模型。通过模型计算,得出在环空堵塞后,堵塞段下部空间的压力随时间的变化规律：在堵塞刚发生时井底压力上升速度较快,随着时间的增加,井底压力上升速度减缓,当地层产气量与堵塞段流如气量相等时压力平稳。 (2)采用实验手段,研究了压力冲破岩屑瞬间的稠密度气固两相流动规律。通过实验数据定量分析了憋堵压力、憋堵岩屑质量与岩屑速度的关系；随着憋堵压力的上升,岩屑颗粒速度近似成线性增加；随着岩屑颗粒总质量的增加,岩屑的速度降低。 (3)通过仿真求解,研究了在压力突破后,高压高速气固两相流从井底流动至井口的流动规律,得出憋堵压力与流动速度的规律。建立了四通井口和安装旋转防喷器的井口的仿真模型,对比了高压高速气固两相流在两种井口流动的流场,发现在相同情况下,四通处的流速和压力均小于旋转防喷器。通过改变边界条件,分析出了随着井底压力上升时四通的受力增加明显旋转防喷器。 (4)研究建立了根据地层情况、工程情况计算井口受力的计算方法,为堵塞后的安全施工提供了理论依据。建议在本文基础上,定量研究解堵压力,为现场卡钻后的解堵提供指导意义。
[Abstract]:In the process of gas drilling, well wall instability may be caused by formation gas production, formation water production or improper construction, which will lead to annulus blockage, which will lead to annulus pressure concentration due to gas injection or gas production after plugging. When the pressure is concentrated to a certain extent, the high pressure gas breaks through the blockage section of cuttings to form a high speed airflow and carries the cuttings to the wellhead, which causes impact and erosion on the wellhead. Therefore, in order to ensure the safety of wellhead, it is necessary to know the impact force and erosion velocity of the wellhead. In this paper, the following research is carried out on the safety of gas drilling under this special condition and some understanding is obtained: 1) by coupling formation percolation model, gas production model, equation of state and Darcy formula, the calculation model of bottom hole pressure is established. Through the model calculation, it is concluded that the pressure in the lower space of the clogging section changes with time after the annulus clogging: the bottomhole pressure rises faster at the beginning of the blockage, and slows down with the increase of time. The pressure is stable when the gas production of the local layer is equal to that of the blocked flow. 2) the law of gas-solid two-phase flow at the moment of pressure breaking through cuttings is studied by means of experiment. According to the experimental data, the relationship between the choking pressure, the quality of the plugging cuttings and the velocity of the cuttings is quantitatively analyzed. With the increase of the choking pressure, the velocity of the cuttings increases linearly, and the velocity of the cuttings decreases with the increase of the total mass of the cuttings. 3) the flow law of high pressure and high speed gas-solid two-phase flow from bottom hole to wellhead is studied by simulation, and the law of choking pressure and flow velocity is obtained. The simulation model of four-way wellhead and well head with rotary blowout preventer is established. The flow field of high-pressure and high-speed gas-solid two-phase flow in two kinds of wellhead is compared. It is found that the velocity and pressure of four-way flow are smaller than that of rotary blowout preventer under the same conditions. By changing the boundary conditions, a rotating blowout preventer with the increase of bottom hole pressure is analyzed. 4) the method of calculating wellhead force according to formation condition and engineering condition is established, which provides a theoretical basis for safe construction after blockage. On the basis of this paper, it is suggested that quantitative study of plugging removal pressure can provide guidance for plugging removal after field drilling.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE28

【参考文献】