JOGMEC 柏崎テストフィールドにおける廃坑作業

抄録

Abstract：Japan Oil, Gas and Metals National Corporation（ JOGMEC） had conducted a plug and abandonment （P&A） operation of experimental well in Kashiwazaki Test Field. The well was drilled in 1992 for ?eld trials of several drilling technologies. After the drilling operation, the well had been utilized for the demonstration of pipe handling in the several training courses around 20 years. However in 2016, the sustained casing pressure （SCP） between 13-3/8 ″ and 20″ casings was observed and we decided to P&A the well. The cause of SCP was assumed to be the gas migration from high pressure gas formation which we encountered in the drilling operation. Thus we thought that the remedy of the cement between 13-3/8″ and 20″ casings would be required for securing the well. First of all, we had conducted engineering study to create a conceptual P&A plan and gather information of the latest P&A technologies. As a result of the engineering study, “Perforate, Wash and Cementing （PWC） tool” was thought to be suitable to secure the well. Then we decided to conduct the well investigation operation to gather the additional information of the well in order to consider the applicability of PWC tool. We obtained Cement Bond Log （CBL） data of the 13-3/8″ casing in the well investigation operation and found that the data indicated good bonding behind the casing. Based on the result of the well investigation, we thought there was a risk of job failure in case we applied PWC tool for P&A operation. Therefore we decided to use a section mill for the P&A operation because it was thought to be the most reliable tool. Finally we successfully secured and properly abandoned the well without any incident, though we encountered the Japan Oil, Gas and Metals National Corporation（ JOGMEC） had conducted a plug and abandonment (P&A） operation of experimental well in Kashiwazaki Test Field. The well was drilled in 1992 for field trials of several drilling technologies. After the drilling operation, the well had been utilized for the demonstration of pipe handling in the several training courses around 20 years. However in 2016, the sustained casing pressure （SCP） between 13-3/8 ″ and 20″ casings was observed and we decided to P&A the well. The cause of SCP was assumed to be the gas migration from high pressure gas formation which we encountered in the drilling operation. Thus we thought that the remedy of the cement between 13-3/8″ and 20″ casings would be required for securing the well.

First of all, we had conducted engineering study to create a conceptual P&A plan and gather information of the latest P&A technologies. As a result of the engineering study, “Perforate, Wash and Cementing （PWC） tool” was thought to be suitable to secure the well. Then we decided to conduct the well investigation operation to gather the additional information of the well in order to consider the applicability of PWC tool.

We obtained Cement Bond Log （CBL） data of the 13-3/8″ casing in the well investigation operation and found that the data indicated good bonding behind the casing.

Based on the result of the well investigation, we thought there was a risk of job failure in case we applied PWC tool for P&A operation. Therefore we decided to use a section mill for the P&A operation because it was thought to be the most reliable tool.

Finally we successfully secured and properly abandoned the well without any incident, though we encountered the several troubles caused by section mill while the P&A operation.