The Key Technologies of Ultra-Deep Hpht Horizontal Wells and Its Application in Shunbei Oilfield of SINOPEC
Authors: Bai Binzhen , Zeng Yijin , Lu Xin , Zhang Hongning , Wang Zhifa , Wang Long , Zhou Haobo , Gramajo Silva Eduardo David , Rached Maurice Rached 
Published: February 2022

There was nearly 1.7 billion tons proved reserve in SINOPEC Shunbei oilfield, which is the deepest (&gt;8000m) fault controlled marine carbonate oilfield in the world with high-temperature (&gt;170 °C) and high -pressure (&gt;140MPa). The formation geological conditions are complicated, high rock strength, easy leakage and collapse, multiple pressure systems co-exist in the slim borehole, which caused a series of directional drilling technical problems such as difficulty in controlling the tool surface, PDM build-up capacity prediction and so on. Therefore, the related research for ultra-deep direction drilling technology were carried out aiming at solving the directional drilling problem for Shunbei oilfield.

Firstly, the optimized wellbore structure scheme design method was proposed, in which the geological characteristics, borehole size and the directional efficiency were considered. And then a double augmented well profile designed model was established based on optimizing the production casing size, through which the directional efficiency and the drilling rate of a trip were increased significantly, and the nonproductive time can be greatly reduced easily. Secondly, an ultra-deep directional well torque transmission prediction model was established based on the mechanical analysis of ultra-deep drilling string and based which a rapid tool face control method was formed. Furthermore, an innovative build-up rate prediction method was established based on both big Data analysis and balanced tendency build-up rate prediction method, and the accuracy is more than 90%. Moreover, the PDM rubber seal, stator and rotor dimensions are optimized to achieve high power output within a certain high temperature range to prolong the service life according to the wellbore temperature field. Finally, the optimization of high temperature MWD instrument and matching process technology was proposed, such as surface assisted cooling, borehole size enlarging and high displacement cooling technology effectively improve the reliability.

The series of ultra-deep directional drilling technology has been applied in Shunbei oilfield. The field application results show that the average ROP of directional section is increased by more than 30%, directional efficiency is greatly improved, and the directional drilling cycle is shortened by more than 20%. Nearly 40 ultra-deep directional wells above 8000m have been constructed, setting more than 10 new Asia records of petroleum engineering onshore directional well.

There are two innovations in this paper. The first is to put forward the design method of wellbore profile with the shortest drilling time as the goal, which can save 1-2 trips and improve the directional efficiency by more than 20%. The second is to introduce the prediction method of build-up rate based on borehole tendency angle, which improves the prediction accuracy of build-up rate by 28% in Shunbei ultra deep directional well.