干旱区生态环境知识资源中心(Arid): Investigation of the Internal Blowout Accident Involving Overpressured Reservoirs: Case of CI-11 Well, Southern Tunisia

Arid

DOI	10.2118/208598-PA
	Investigation of the Internal Blowout Accident Involving Overpressured Reservoirs: Case of CI-11 Well, Southern Tunisia
	Khalfi, Chaouki; Ahmadi, Riadh
通讯作者	Khalfi, C
来源期刊	SPE DRILLING & COMPLETION
ISSN	1064-6671
EISSN	1930-0204
出版年	2022
卷号	37 期号:2 页码:104-117
英文摘要	This study consists of an assessment of the ecological accident implicating the Continental Intercalaire-11 (CI--11) water well located in Jemna oasis, southern Tunisia. The CI-11 ecological accident manifested in 2014 with a local increase of the complex terminal (CT) shallow water table salinity and temperature. Then, this phenomenon started to spread over the region of Jemna, progressively implicating farther wells. The first investigation task consisted of logging the CI-11 well. The results revealed an impairment of the casing and cement of a huge part of the 9. in. production casing. Historical production records show that the problems seem to have started in 1996 when a sudden production loss rate occurred. These deficiencies led to the CI mass-water flowing behind the casing from the CI to the CT aquifers. This ecological accident is technically called internal blowout, where water flows from the overpressurized CI groundwater to the shallower CT groundwater. Indeed, the upward CI hot-water flow dissolved salts from the encountered evaporite-rich formations of the Lower Senonian series, which complicated the ecological consequences of the accident. From the first signs of serious water degradation in 2014 through the end of 2018, several attempts have been made to regain control of annular upward water flow. However, the final CT groundwater parameters indicate that the problem is not properly fixed and communication between the two involved aquifers still persists. This accident is similar to the OKN-32 case that occurred in the Berkaoui oil field, southern Algeria, in 1986, and included the same CI and CT aquifers. Furthermore, many witnesses claim that other accidental communications are probably occurring in numerous deep-drilled wells in this region. Concludingly, Jemna CI-11, Berkaoui OKN-32, and probably many other similar accident cases could be developing regional ecological disasters by massive water resource losses. The actual situation is far from being under control and the water contamination risk remains very high. In both accidents, the cement bond failure and the choice of the casing point are the main causes of the internal blowout. Therefore, we recommend (1) a regional investigation and risk assessment plan that might offer better tools to predict and detect earlier wellbore isolation issues and (2) special attention to the cement bond settlement, evaluation, and preventative logging for existing wells to ensure effective sealing between the two vulnerable water table resources. Besides, in the CI-11 well accident, the recovery program was not efficient and there was no clear action plan. This increased the risk of action failure or time waste to regain control of the well. Consequently, we suggest preparing a clear and efficient action plan for such accidents to reduce the ecological consequences. This requires further technical detailed study of drilling operations and establishment of a suitable equipment/action plan to handle blowout and annular production accidents.
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000812367100001
WOS关键词	CONTINENTAL INTERCALAIRE ; REGIONAL GRAVITY ; RESIDENCE TIME ; AQUIFER SYSTEM ; NEFZAOUA BASIN ; GROUNDWATER ; WATER ; DEEP
WOS类目	Engineering, Petroleum
WOS研究方向	Engineering
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/394526
推荐引用方式 GB/T 7714	Khalfi, Chaouki,Ahmadi, Riadh. Investigation of the Internal Blowout Accident Involving Overpressured Reservoirs: Case of CI-11 Well, Southern Tunisia[J],2022,37(2):104-117.
APA	Khalfi, Chaouki,&Ahmadi, Riadh.(2022).Investigation of the Internal Blowout Accident Involving Overpressured Reservoirs: Case of CI-11 Well, Southern Tunisia.SPE DRILLING & COMPLETION,37(2),104-117.
MLA	Khalfi, Chaouki,et al."Investigation of the Internal Blowout Accident Involving Overpressured Reservoirs: Case of CI-11 Well, Southern Tunisia".SPE DRILLING & COMPLETION 37.2(2022):104-117.