PROBLEMS OF HORIZONTAL WELL DRILLING COMPLETION

Abstract

The article analyzes factors affecting the quality of horizontal well construction. The role of drilling fluid and the criteria for its selection are highlighted, among which the principal ones include: cleaning the horizontal wellbore, maintaining the stability of the walls of the well, reducing frictional forces and maintaining the permeability of the reservoir. In horizontal wells, the actual path must correspond to the design path, ensuring that it reaches the tolerance circle. At the same time, almost half of wells during drilling process require correction of the trajectory. The schemes of barefoot open-hole completions, with the lowering of perforated liners or the descent of the production casing with subsequent cementation and perforation are reviewed. Barefoot open-hole is the most economical, but there is a tendency of collapse of the wellbore, removal of sand, difficulties in carrying out work pertaining to the isolation of water and gas. Perforated liner prevents the wellbore from collapsing. However, it is difficult to isolate the zones of water or gas penetration. Completion by lowering and cementing the casing leads to the prevention of wellbore collapse, control gas and water-oil contact, as well as to isolate the water inflow zones at any stage of production. Horizontal wells are more sensitive to pollution than vertical wells. The coefficient of reservoir penetration recovery in a horizontal well is 17-20% less than in a vertical well. For successful cementing of horizontal wells, it is necessary to ensure a thorough cleaning of the wellbore and a good centering of the casing with the use of rigid or spring centralizers. The perforation of horizontal wells presents a certain level difficulty, due to the need to lower the perforator on the drill string. The use of a perforated liner equipped with magnesium plugs is considered.