Application of Constant Pressure Explosive Floating Casing Technology in Large Displacement Horizontal Wells

Abstract

Large displacement horizontal wells are commonly employed to enhance unconventional resource recovery. However, during the field process, challenges often arise, particularly in cases where the casing string cannot reach the designated position. This issue is particularly prominent in the development of shallow wells with long horizontal segments. Currently, widely adopted traditional floating casing methods fall into two main categories: mechanical and rupture disc types. Mechanical methods faces the challenge that after casing running, the mechanical separation structure remains in the wellbore, adding difficulties to subsequent operations. Rupture disc methods face the challenge of pressure misalignment due to factors such as excitement pressure in the liquid column, potentially leading to premature opening during descent. This paper presents a constant pressure explosive floating casing method, characterized by large reliability and the elimination of the need for additional drilling to remove the barrier structure after casing lowered. This paper focuses on two main aspects: firstly, the design of two-stage initiation mechanisms, corresponding to the initiation pressure of the exciting device and the crushing pressure of the rupture disc. This design ensures precise initiation at low pressure levels while maintaining pressure integrity. Secondly, for different well conditions, varying initiation pressures can be selected, allowing for targeted optimization of initiation and crushing pressures while keeping the pressure difference consistently within a safe range, preventing inadvertent opening and failure during the descent process. In field application, the constant pressure explosive floating casing technology has been successfully applied in over 100 wells, with the longest floating segment reaching 3270m. In all cases, the casing descended smoothly to the designated position, offering convenient, safe operations without the need for repeated plugging. This technology guarantees the attainment of the design-required opening pressure and ensures full wellbore diameter and sealing integrity. The technology effectively avoids the complexities associated with casing installation in long horizontal, large-displacement wells, reducing the difficulties in subsequent operations such as cementing and completion.