Simulation Study On Erosion Of Prefabricated Pore Eyes In Horizontal Wells Of Carbonate Reservoirs

Matrix acidizing is an important method to stimulate and remove damage in carbonate reservoirs. As for horizontal wells, it is the key to optimize diverting and acid placement along the well interval in order to achieve uniform damage removal and successful acidizing.In this paper, for the purpose of efficient damage removal, acidizing through prefabricated holes on the operation string was proposed based on the characteristics of formation damage in the horizontal wells. Besides, studies of acid distribution regularity, acid-rock reaction, wormholes formation, and simulated calculation of stimulation performance were also conducted.(1) Damage model for horizontal wells is established, which considered the influence of skin factor and damage radius; identified the requirements for acid distribution; provided guidance for the research and design of acidizing fluid placement.(2) Prefabricated Hole Acid Jet technology was proposed. The flow field in the perforation jet was simulated with the FLUNET software; factors influencing pressure and velocity in the flow field were studied, as well as their influence law; the pressure boundary on the bottom hole wall was ascertained under different perforation and acidizing parameters.(3) Acidizing model for carbonate reservoir horizontal well was established. Take the pressure distribution on the surface of the wall during acidizing as the inner boundary conditions of the acidizing model, and couple the flow from prefabricated hole to surface to solve this model. In this way, we can predict the acid quantity and descript the reactions in each section.(4) Studied various influence factors, including the acidizing capacity, the prefabricated hole parameters and reservoir damage degree, etc. and their effect on the acid-etched wormhole formation and propagation. Aiming at reservoir condition, recommended acidizing capacity, prefabricated hole parameters and arrangement way of prefabricated holes, which can provide design method for acidizing.(5) Stimulation ratio model was established. The General Acidification and the Hole Prefabricated Jet Acid can use this model to compare their efficiency in acid placement, the condition of the skin factor changes after acidizing. We can use this method to evaluate the acidizing effect and measure the economic efficiency. This will provide some basis to choose the preferred option before acidizing.In this paper, the author launched a complete plan for carbonate reservoir horizontal well Prefabricated Hole Acid Jet technology and matched methods with design and numerical simulation. It can guide the design and apply in the oil field. The simulation showed the implementation of this technology can improve treatment performance significantly.