SPECIFICS OF WELL KILLING TECHNOLOGY DURING WELL SERVICE OPERATION IN COMPLICATED CONDITIONS

The process of the well killing operations in the oil and gas condensate field in Volga-Ural province is complicated due to several conditions like fractured carbonate reservoir, abnormally low reservoir pressure, high gas-oil ratio, high hydrogen sulfide content, acid fracturing, and hydrochloric acid treatments requirement. During the well killing process, significant gas breakthroughs and fluid loss are observed in this field, which requires significant usage of blocking compositions (up to 50-100 m3 per single well) and increases the well service costs. The aim of this work was to increase the well killing efficiency during well service by studying the mechanisms that take place near the wellbore zone during this process. The application of statistical and multifactor analysis of well-killing processes were conducted from 2018 to 2019, which allowed highlighting the main reasons for the low success of these works. The calculation results showed that the stress state near the well significantly differs from the regional stress field and varies depending on the generated pressure in the well, which in turn affects the activity of fractures near the wellbore. The revealed mechanisms that take place near the wellbore zone coupled with the laboratory and pilot tests of the blocking compositions can be used to improve the well service operations at the oil and gas condensate field in the Volga-Ural province. In this work, it was concluded that it is important to use the geomechanical approach to increase the well killing efficiency in combination with a complex of laboratory rheological and filtration tests of blocking compositions.

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Success Implementation of Pressurized Mud Cap Drilling in Offshore East Java Prospect, Avoid Rig Flat Time During Loss Circulation and Continue Drilling with 400psi in the Annulus to Reach Target Depth Through Fractured Carbonate Formation in 2 Days

10.2118/207752-ms ◽

2021 ◽

Author(s):

Irawan Fikri ◽

Ali Ali ◽

Ismi Airil ◽

Prasthio Andry ◽

Setiawan Teguh ◽

...

Keyword(s):

Oil And Gas ◽

Field Operator ◽

Control Device ◽

Drill String ◽

Lessons Learned ◽

Carbonate Reservoir ◽

Total Loss ◽

Carbonate Formation ◽

Fractured Carbonate ◽

Target Depth

Abstract The offshore East Java laid numerous carbonate formation, where depending on area, carbonate formation is exercised as the reservoir. The carbonate exploration drilling campaign, which is naturally fractured, risks the operation not just from safety aspect but also deliverability of well objective to explore uncovered reserve in the area. In this well, total loss circulation was experienced while drilling, despite no record of similar event from offset wells data. The field operator determined to call out Rotating Control Device (RCD) and installed prior to drilling 12.25in. hole section. The Pressurized Mud Cap Drilling (PMCD) method is prepared in advance as mitigation plan to overcome the exploration uncertainties. PMCD is one of the Managed Pressure Drilling (MPD) variants used in oil and gas wells that experience severe to total loss circulation. PMCD method involves drilling with closing flowline valve completely while using RCD system to seal the annulus. While drilling the 12.25in section, absence of return fluid observed as drill string penetrates the carbonate reservoir section (target formation). Activation of the annulus flooding system enables to pumps seawater through annulus, continued with pulling out the string to last casing shoe, and then installation of RCD bearing assembly to convert drilling strategy into PMCD method. As the PMCD components required such as RCD and drill string Non-Return Valve already equipped and all associated procedures prepared in advance, swift transition to PMCD mode results to lesser drilling flat time. After reaching target depth, the PMCD setup also assists in the deployment of open hole logging operation by installing RCD logging adaptor. With the successful PMCD implementation, the field operator managed to reduce drilling risks, reach exploration target successfully, reduce flat times and increase in ROP. This paper present success story of PMCD well drilled and lessons learned as the operator evolves to improve PMCD execution further.

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