Newly Designed Flow Activated Pulsation Tool for Coiled Tubing Deployed Matrix Acidizing Stimulation Applications in Extended Reach Carbonate Reservoirs

摘要

Matrix acid stimulation throughout a well's life cycle is a common technique applied to wells with impaired productivity. Coiled tubing (CT) is often chosen as the conveyance means for delivering the acid treatment in horizontal wells to the damaged zones, and in applying an effective chemical divergent for highly permeable zones. Due to the nature of helical buckling, weight stacking, and wellbore geometry, the CT operation is often limited in its ability to reach total depth (TD). In short horizontal wells with slight reservoir contact, conventional methods such as pumping lubricant fluid are used to overcome the effect of drag and friction on the CT. For extended reach wells, a downhole pulsation tool is placed on the bottom-hole assembly (BHA) adding axial vibration, which reduces the frictional forces, delaying the onset of CT helical buckling. The compounding increase in friction as more coil is introduced significantly reduces the effect of the pulsation tool, often resulting in its inability to advance the coil to TD. To tackle this challenge, a more responsive flow activated pulsation tool (FAPT) was developed, providing excitation over an increased length of coil to continuously break the friction at each new contact point without sacrificing frequency and pulse magnitude. The new generation flow activated pulsation tool was developed by re-thinking the design philosophy, creating a new pulsation mechanism to meet the objective of extending the CT reach in restricted extended reach wells. The development was completed after testing a series of different valve section designs to determine the optimum generated pulse magnitudes that would increase the overall pull force. The developed tool produces stronger and higher performing pulses. Additionally, the new design focuses on reducing the activation flow rate of the tool down to approximately one barrel per minute. This improves the operational efficiency and reduces the total volume of fluid required on the job location. This study focuses on the FAPT development and the results of using the new tool on the first two global trial runs. The two wells were drilled as oil producing horizontalwells with 19,000 ft to TD. The wells wrere completed as open hole with electric submersible pumps (ESPs) and a 2.44" restriction to allow well intervention. The intended goal was achieved in both runs by reaching TD, which allowed for effective acid treatments.