This article is based on field data obtained after seven sessions of bottom-hole zone treatment (BHZT) that were performed in horizontal wells in 2013 and featured fresh water and degassed oil injection for the purpose to restrict the amount of produced breakthrough gas.
This article includes the results of monitoring the performance of the wells before and after the BHZT. It contains information about a new approach to assessment of the well intervention techniques (WIT) with consideration of the effect of decreasing the amount of produced breakthrough gas. The article also contains brief information about other methods of eliminating gas breakthroughs applied by OOO "LUKOIL-Nizhnevolzhskneft".
In 2016, the first application in Russia of a diversion technology with multimodal granules was performed during matrix treatment of a carbonate reservoir in a water-absorbing well in an offshore field in the northern Caspian Sea.
The operator's main objectives were the recovery of water-absorbing well injectivity while simultaneously straightening the profile by a temporary isolation of high-absorbing intervals. To achieve the objectives, two operations needed to be performed: large-volume acidizing of J3V Volgian regional stage and acid spotting in the interval of the Neocomian superstage.
Korchagin oilfield is located in the northern part of the Caspian Sea. Drilled wells are mega-reach (MD/TVD ratio greater than 3.0) with measured total depth (MD) up to 23,622 ft [7,200 m] and vertical depth of only 5,118 ft [1,560 m]. This presented a great challenge for coiled tubing (CT) well intervention even with the help of state-of-the-art hydraulic tractors. Limited working area, weight restrictions, challenging well geometry, completion features and lack of experience in offshore CT operations in the North Caspian Sea, required complex pre-job activities to optimize job design, select proper downhole tools and prepare a robust layout plan. This paper will illustrate the project preparation challenges, on-the-job troubleshooting and workflow, supported by the well case studies and results from the first CT operation in Northern Caspian Offshore. Lessons learned from the project, where all defined objectives were achieved with zero HSE (health, safety and environment) incidents, were also captured to assist in future campaigns with similar operational environment.
The Caspian Sea region, which includes Russia, Azerbaijan, Kazakhstan, Turkmenistan, Uzbekistan, and Iran, is one of the oldest oil-producing areas in the world and is an increasingly important source of global energy production. The area has significant oil and natural gas reserves from both offshore deposits in the Caspian Sea itself and onshore fields in the region.
Korchagin oilfield is located in the northern part of the Caspian Sea. Drilled wells are mega-reach (MD/TVD ratio greater than 3.0), with measured depths (MD) up to 23,622 ft and vertical depths of only 5,118 ft. This presents a great challenge for any well interventions, even for Coiled Tubing (CT) equipped with state-of-the-art hydraulic tractors. Limited working area, weight restrictions, challenging well geometry, completion features and lack of experience in offshore CT operations in the North Caspian Sea, required complex pre-job activities to optimize job design, select proper downhole tools and prepare a robust layout plan. This paper illustrates North Caspian project preparation challenges, on-the-job troubleshooting and workflow, supported by the well case studies and results from the first CT operation in North Caspian Offshore. Lessons learnt from the project, where all defined objectives were achieved with zero HSE (health, safety and environment) incidents, were also captured to assist in future campaigns with similar operational environment.
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