Odiete William Ejuvweyerome
Department of Petroleum Engineering, Delta State University, Abraka Oleh Campus, Oleh, Delta state, Nigeria.
Heliyon. 2022 May 13;8(5):e09404. doi: 10.1016/j.heliyon.2022.e09404. eCollection 2022 May.
Failure and poor performance of logging tools in high pressure-high temperature wells; the associated technical consequences and the resultant high cost of logging operations are recurrent problems in the oil & gas industry worldwide. The aforesaid prompted this work to invent the "New Wellbore Temperature Control Design" for protection of logging tools against high bottom-hole temperatures. It hinges on the novel concept of thermal drainage radius and the temperature-drop effect of chilled oil-based mud to reduce bottom-hole temperature prior to logging. The methods applied include laboratory testing, mathematical modeling and design. The novel concept of "thermal drainage radius" quantified the radial extent of temperature-drop effect in the formation, away from the wellbore. Novel mathematical models were also invented. Laboratory results showed that the formation temperature-drop from bottom-hole temperature to thermal equilibrium temperature increased with bottom-hole temperature per chilled oil-based mud. The temperature-drop duration and temperature-rise duration increased with bottom-hole temperature per chilled oil-based mud. The temperature-rise duration increased with decrease in the temperature of the chilled oil-based mud per bottom-hole temperature. Job design results showed that when placed in the zone of interest in the wellbore the heat energy absorbed increased with quantity of the chilled oil based mud but the temperature rise duration decreased with increasing heat transfer rate from the formation and vice versa. Furthermore, results revealed that the higher the thermal conductivity of the formation, the longer the thermal drainage radius and vice versa. The logging operation should commence after placement of the chilled oil-based mud in the zone of interest (no circulation of the chilled oil-based mud) and be completed before the end of the temperature-rise duration. Oil-based mud is cheap and available in every country unlike the expensive vacuum flasks and thermal insulating jackets currently used for protecting logging tools against high temperature. The new wellbore temperature control design has global applicability.
在高压高温井中测井工具出现故障及性能不佳的情况；相关的技术后果以及由此导致的测井作业成本高昂，是全球石油和天然气行业反复出现的问题。上述情况促使开展这项工作，以发明“新型井筒温度控制设计”来保护测井工具免受井底高温影响。它基于热排水半径的新概念以及冷却油基泥浆的降温效果，在测井前降低井底温度。所应用的方法包括实验室测试、数学建模和设计。“热排水半径”这一新概念量化了地层中远离井筒的降温效果的径向范围。还发明了新颖的数学模型。实验室结果表明，每冷却油基泥浆，地层温度从井底温度降至热平衡温度的降幅随井底温度升高而增大。降温持续时间和升温持续时间随每冷却油基泥浆的井底温度升高而增加。升温持续时间随每井底温度冷却油基泥浆温度的降低而增加。作业设计结果表明，当置于井筒中的感兴趣区域时，吸收的热能随冷却油基泥浆量增加而增加，但升温持续时间随地层传热速率增加而减小，反之亦然。此外，结果表明地层的热导率越高，热排水半径越长，反之亦然。应在将冷却油基泥浆置于感兴趣区域后（冷却油基泥浆不循环）开始测井作业，并在升温持续时间结束前完成。与目前用于保护测井工具免受高温影响的昂贵真空瓶和隔热套不同，油基泥浆价格便宜且在每个国家都有。这种新型井筒温度控制设计具有全球适用性。
