????通訊員 據今日油價3月2日報道，“地熱十年”這句話在媒體和能源行業的聚會上越來越常見，因為國際凈零排放計劃包括了從地球上提取能源的最吸引人和最清潔的方式之一：地熱發電。
????為了達到地球地幔輻射到地核的熱量，地熱公司需要鉆探——而且需要鉆得很深。事實上，這個新興行業面臨的最大挑戰之一是鉆到足夠深的地方，以達到真正的高溫。但是，鉆這么深是有風險的，也是昂貴的。
????然而有報道稱，地熱即使在更小的深度也能發揮相當大的作用。根據Rystad Energy最近的一項分析，要從地熱井中加熱的汽化水中發電，發電設施需要240至300攝氏度的溫度。該分析還指出，目前多達70%的地熱產出用于發電。
????事實上，無論明智與否，人們都渴望讓一切都電氣化，這一切都與電有關，更具體地說，是無排放的電。地熱非常適合這樣做：雖然地熱井的鉆探確實涉及使用化石燃料的設備，但從壽命的角度來看，地熱與風能和太陽能完全可比，考慮到它們需要的材料，風能和太陽能也并非完全無排放。
????然而，由于高昂的前期成本和對鉆探結果的普遍不確定性，地熱能發展緩慢。行業專家總是注意到，我們腳下到處都是“熱能”，但他們也強調，并不是所有的“地熱”都那么容易，或者說可以以非常經濟的方式達到。冰島一直是一個很好的例子，因為它的地熱資源很容易獲取，還有意大利和土耳其。
????難怪地熱領域的大量工作都集中在使更深層鉆探更經濟的技術上。大型石油公司的加入對石油行業來說是件好事。畢竟，這些公司進入地熱領域最有意義，因為他們最了解鉆探技術。
????說到石油，一些公司一直在研究和測試一些東西，可以擴大地熱能的范圍，使石油公司受益——將廢棄的油井變成地熱能井。
????有一些公司正在朝著這個方向努力，要么把廢棄的油井變成地熱井，要么讓它們成為既能產生熱量又能產生石油的兩用井。從理論上講，將油井改造為地熱井對促進地熱的普及有很大的幫助。然而，實際上，這并不是那么簡單。
????德克薩斯大學奧斯丁分校地熱創業組織的Jamie Beard表示，首先，這類井的流量遠低于新鉆的地熱井。其次，在發電方面，大多數油井的溫度根本不足以產生經濟意義。第三，Beard表示：“現有的油井經常遭受油井完整性問題的困擾，這將使它們不適合作為一種生產地熱資產使用20-40年。”
????好消息是，這并不意味著把廢棄井變成熱能利用井是完全不可能的。記住，發電是地熱鉆探的主要目的，但供暖作為一個應用領域也不應被低估。
????一些公司利用廢棄的井注入水，加熱，然后用來取暖。如果油井選擇正確，發電也不是不可能的。然而，廢棄的水井似乎更適合供暖。
????英國律師事務所Fieldfisher油氣業務主管保羅?斯托克利(Paul Stockley)表示，即便是在這個領域，也存在挑戰。其中一個問題是，水需要在井中停留多長時間才能變得足夠熱。此外，成本也應該要注意。
????廢棄的井似乎最適合作為附近建筑物和設施的熱源。斯托克利指出，可以用于農業作業。因為在英國，大多數陸上油井都在農田附近，所以這種匹配幾乎是完美的。
????因此，并不是所有的廢棄油井都適合轉化為地熱儲層。然而，一些人可能會獲得二次利用機會，然后可以用來加熱附近的設施。總的來說，對于發電來說，新的鉆探似乎是目前更好的選擇。而且，與其他任何技術一樣，成本必將繼續下降，特別是在大型石油投資的幫助下。甚至還出現了利用地球地熱資源的新研究領域：廢棄煤礦的利用。
????王佳晶 摘譯自 今日油價
????原文如下：
????Can Abandoned Oil Wells Be Used To Generate Geothermal Power?
????“The decade of geothermal” is a phrase that is becoming increasingly common in media and energy industry gatherings as the international zero-emission push comes to include one of the most fascinating—and clean—ways of extracting energy from the earth: geothermal power.
????To reach the heat that the mantle of the Earth radiates into the core, geothermal companies need to drill—and they need to drill deep. In fact, one of the biggest challenges for this emerging industry is drilling deep enough to get to the really high temperatures: drilling so deep is risky and costly.
????Yet geothermal can do pretty well even at smaller depths. According to a recent analysis by Rystad Energy, to generate electricity from the vaporized water heated up in geothermal wells, a power generation facility needs temperatures of 240 to 300 degrees Celsius. The analysis adds that as much as 70 percent of geothermal output right now is used for electricity generation.
????Indeed, with the urge to electrify everything—whether this is wise or not—it’s all about electricity and, more specifically, emission-free electricity. Geothermal is perfect for this: while the drilling of a geothermal well does involve equipment that uses fossil fuels, from a lifetime perspective, geothermal is fully comparable with wind and solar, which are also not entirely emission-free given the materials they need to operate.
????Yet geothermal has been slow to take off because of the high upfront costs and the general uncertainly about the result of drilling. Industry experts invariably note that the heat is everywhere beneath us, but they also make a point of emphasizing that not all of that heat is that easy—or economical—to reach. Iceland is always a case in point with its easily reachable geothermal resources, as well as Italy and Turkey.
????No wonder then that a lot of effort in geothermal has focused on the technology to make deeper drilling economical. It’s been a boon for the industry that Big Oil has joined the party. After all, these are the companies whose entry into geothermal makes the most sense, given they know drilling best.
????Speaking about oil, some companies have been researching and testing something that could expand geothermal’s reach and benefit oil companies: turning abandoned oil wells into geothermal wells.
????There are a few companies working in this direction, either turning abandoned wells into geothermal ones or making them double-use wells that yield both heat and oil. Theoretically, the transformation of oil wells into geothermal wells can be of great help for boosting geothermal’s popularity. Practically, however, it’s not that straightforward.
????For starters, flow rates from such wells are much lower than from newly drilled geothermal wells, Jamie Beard from the Geothermal Entrepreneurship Organization at the University of Texas at Austin told Oilprice. Then there is the issue of heat: most oil wells are simply not hot enough to make economic sense if we are talking about electricity generation. Thirdly, Beard says, “existing wells often suffer from well integrity issues that will make them ill-suited for a 20-40 year lifespan as a producing geothermal asset.”
????The good news is this does not mean turning abandoned wells into heat-producing reservoirs is completely off the table. Remember, electricity generation is the main purpose of geothermal drilling but heating should not be underestimated as an area of application, either.
????Some companies are using abandoned wells to inject water into them, heat it, and use it for, well, heating. Power generation is also not out of the question if the well is right. Yet it seems that abandoned wells are better suited for heating purposes.
????Even in that area, however, there are challenges, says Paul Stockley, head of Oil and Gas at UK-based law firm Fieldfisher. One of these is how long the water needs to stay in the well to become hot enough to be used for heating. The longer the time, the lower the viability of the system. Costs should also be borne in mind, Stockley notes. Even if drilling costs are taken out of the equation, there is injection equipment and transfer-of-heat equipment to consider.
????It appears that abandoned wells are most viable as a heating source for nearby buildings and installations. For instance, Fieldfisher’s Stockley notes agricultural operations that can be heated. Since in the UK most onshore oil wells are near farmland, the match is almost perfect.
????Not all abandoned oil wells, then, are suitable for converting into geothermal reservoirs. Some may, however, get a second life to heat up water that could then be used to heat a nearby facility. For electricity generation, new drilling appears to be the better option for the time being, overall. And, as with any other technology, costs are bound to continue falling, especially with the help of Big Oil investment. There are even new areas of research into harnessing the geothermal resources of the planet: flooding abandoned coal mines and using the water heated in this way to generate electricity and use it for heating and cooling.
