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

Abstract

Matrix acid stimulation throughout a well’s life cycle is a common technique applied to wells with impaired productivity. Coiled tubing is often chosen as the conveyance means for delivering the acid treatment in horizontal wells to the damaged zones and in applying effective chemical divergent for highly permeable zones. Due to the nature of helical buckling, weight stacking, and wellbore geometry, the coiled tubing operation is often limited in its ability to reach total depth (TD). In short horizontal wells with slight reservoir contact, conventional methods are used to overcome the effect of drag and friction on the CT; such methods include pumping lubricant fluid. In more challenging applications and extended reach wells (ERW’s), a downhole pulsation tool is placed in the bottomhole assembly to add some axial vibration to the string and exert a pulling force to delay the onset of CT helical buckling, which, in turn, increases the reach of the coil. The significant reduction in friction is caused by the Flow Activated Pulsation Tool (FAPT), which allows the CT to increase its coverage and reach the desired target depth. A new FAPT generation was developed by designing a new valve section to meet the objective of extending the CT reach in highly restricted (2.44") ERW’s. The development of the new valve section was completed after series of testing different valve sections to determine the optimum generated pulses that would increase the overall pull force at the lowest activation flow rate. The newly developed tool offers a stronger and higher performing pulses at lower activation flow rate, allowing it to operate effectively in more challenging ERW’s. The FAPT development and the results of using the new tool after the first two global trial runs. The two wells were drilled as oil producing horizontal wells with +18,000 feet to TD. The wells were completed as open hole with electric submersible pumps (ESP’s) and a 2.44’’ restriction to allow well intervention. In both runs, the goal was achieved by reaching TD of the openhole section with effective placement of the acid treatments.