Targeted-Acidizing Tech Meets Various Goals in Long Horizontal Wells: Enhance Productivity or Equilibrate Flow Profile

CT (coiled tubing) acidizing is the main work before horizontal wells put into production in the Middle East. The targeted stimulation interventions directly affect the afterwards performance of production and injection wells. This work not only highlights the importance of removing damage to enhance productivity of producer in the initial production stage, but also put forwards the effective measures of equilibrating flow profiles of injector and producer in the stable production stage. The real-time acidizing techniques combined with distributed temperature sensing (DTS) is used to equilibrate inflow profile in injectors successfully. However, it is lack of effective measures or BHA to guide removing the un-uniform damage and improving acid absorbing in poor interval of horizontal producers. Combined with logging interpretation data and drilling parameters, a velocity-based un-uniform damage model is developed to understand the drilling fluid displacement, mixture and diffusion process in the reservoir-scale. To help ensure accurate acid placement in producer at different production stages, a targeted-acidizing idea is proposed based on the quantitative prediction of inflow and skin factor profiles. To compare the acidizing efficiency between various proposals and illustrate the effectiveness of targeted-acidizing design, A three-dimensional diverted-acidizing simulator is developed for carbonate reservoir, and applied in AHDEB Oilfield, Iraq. According to the simulation of various acidizing designs in new producer, the acid placement based on skin factors can receive the highest productivity compared with traditional uniform, cone-shaped or permeability-based acidizing measures. In the case study, 3 typical acidizing targets cooperated with re-open work of producer have been proposed. The injection rate and acid volume have been optimized through simulation. In order to make under-stimulated intervals absorbing more acid and avoid connecting thief layers, the CT selective acid jetting plus drag back tech is introduced. The production performance after acidizing shows that the stimulation ratio reaches to 7 times. The water cut is also controlled very well. It is difficult to enhance productivity and equilibrate flow profile at the same time under the limited acidizing scale, especially in the long horizontal wells (over 1000m). this paper highlights which goals we should consider firstly at different production stages, and give out the effective measures of evaluation and execution in the matrix acidizing procedure of horizontal wells.