Prediction of wax precipitation region in wellbore during deep water oil well testing

• Published in: Petroleum exploration and development 2018-04, Vol.45 (2), p.351-357
• Main Authors: GAO, Yonghai, LIU, Kai, ZHAO, Xinxin, LI, Hao, CUI, Yanchun, XIN, Guizhen, SUN, Baojiang
• Format: Article
• Language: English
• Subjects: deep water oil and gas development; oil well testing; pressure field; temperature field; wax precipitation region prediction; wellbore wax precipitation
• ISSN: 1876-3804; 1876-3804
• DOI: 10.1016/S1876-3804(18)30039-9

During deep water oil well testing, the low temperature environment is easy to cause wax precipitation, which affects the normal operation of the test and increases operating costs and risks. Therefore, a numerical method for predicting the wax precipitation region in oil strings was proposed based on the temperature and pressure fields of deep water test string and the wax precipitation calculation model. And the factors affecting the wax precipitation region were analyzed. The results show that: the wax precipitation region decreases with the increase of production rate, and increases with the decrease of geothermal gradient, increase of water depth and drop of water-cut of produced fluid, and increases slightly with the increase of formation pressure. Due to the effect of temperature and pressure fields, wax precipitation region is large in test strings at the beginning of well production. Wax precipitation region gradually increases with the increase of shut-in time. These conclusions can guide wax prevention during the testing of deep water oil well, to ensure the success of the test.