Didin Chaerudin Irwansyah(1), Dicky Alamsyah(1), Pradana Vian Prasetyo(1), Vicki Agustino(1), Budi Setiawan(2), Ingria Yunandra M. Arrasy(2), Zakki Sabiq Purwaka(2), Jarot Pambudi(2)
[1]Rigsis Energi Indonesia, [2]Geo Dipa Energi
ABSTRACT
The cementing of production casing in geothermal well constructions is a critical activity that determines well integrity. Given that production steam flows in contact with the production casing, it is imperative that the casing and cement exhibit sufficient strength to maintain a reliable seal throughout the well’s useful lifetime. Wells constructed in the 90s and early 2000s utilized the long-string cementing method. However, contemporary wells employ the tie-back cementing method, allowing the separation of running casing and cementing into two stages.
The primary concept behind the tie-back method is to reduce the hydrostatic pressure of the cement slurry in the first stage, thereby minimizing destructive effects on weak zones. The success of tie-back cementing is gauged by three key parameters obtained in the first stage: shear pin pressure, bump plug pressure, and the occurrence of a ‘u-tube’ when releasing the liner running tool. The absence of any of these three parameters can adversely affect the quality of cement in the shoe and annulus, potentially compromising cement integrity.
This paper provides a summary of the operational aspects of tie-back cementing in Indonesia’s D and P Fields, covering 21 wells during the drilling campaign. Seventeen of these wells achieved successful tie-back cementing operations, as evidenced by the attainment of shear pressure and bump plug. The remaining four wells failed to achieve bump plug and/or shear pressure, necessitating further remedial cementing. Various approaches were employed in the D and P Fields to ensure successful tie-back cementing operations, which are detailed in this paper for the purpose of sharing lessons learned.
An observed best practice for achieving optimal cement results involves an extensive wiper trip with polish operation, particularly within intervals where dog leg is high, before running the liner. This ensures that the well is slick and approaches the ideal shear pressure.
