Effective Wellbore Cleanup and Improvement of Injection Performance and Conformance Using Coil Tubing Conveyed Tool for Waveform Dominated Fluid Dispersion and Pin-Point Chemical Placement During Well Stimulation
Authors: Nagar Ankesh , Davidson Brett , Srivastava Preyas , Verma Nakul , Shrivastava Pranay , Nekkanti Satish Kumar , Bohra Avinash , Vermani Sanjeev 
Published: March 2020

Poor conformance is a major concern of Mangala, Bhagyam & Aishwarya (MBA) fields. The presence of high permeability streaks or thief layers between injection and production wells typically results in pre-mature water breakthrough, high water cut and deficient volumetric sweep. As a result, significant oil volumes in the reservoir may not be contacted by the injection fluid. Another concern is of low VRR (Voidage Replacement Ratio) in some of the layers due to reduced injectivity in those sands. Consequently, it has led to poor recovery from those sands. It is also a growing problem with the polymer deposition taking place in the wellbore particularly Mangala (undergoing full-field polymer flooding), leading to challenging wellbore cleanup operations.

Several methods have been used in the past, both mechanical and chemical to improve the treatment fluids during stimulation. In this paper, we introduce a novel placement technique for Conformance Improvement which is practical, effective and durable as well as another tool variant that helps cleanup challenging wellbore environments. Typically, prior to the tool allowing for pin-point placement, the adjustable nozzle tool is run to ensure that the perforation and wellbore is cleaned up thoroughly with help of advanced fluid dynamics. The dynamic injection modulation (hereinafter referred to as, "DIM") tool for pin-point stimulation placement improves the distribution of injected fluid in the reservoir matrix by the process of dispersion. The tool generates an energized fluid pulse that allows fluid to be diverted away from established fluid paths. The pressure pulse, as it travels dilates the pore spaces thus propagating the wave further into the reservoir. The pin-point accuracy of placements leads to treating of reservoir layers which are left untreated during conventional stimulation treatments where viscous fingering effects dominate. As a result, injection fluid would divert into uncontacted layers to improve sweep efficiency. The other advantage of the tool is the relatively easy integration of tool with existing infrastructure. The tool is easily run with coiled tubing ("CT") with only addition of an accumulator unit on surface.

This paper will document the tool physics, job design and Implementation technique for stimulation using Fluid Modulation tool as well enhanced well cleanup. Particular attention is paid to multiple injector and producer well stimulation case studies from these fields, the challenges faced, the solution proposed, and finally the results obtained. The results observed across the field with respect to injection performance is consistently greater than 75% over conventional methods used earlier. Also specifically, in scenarios of difficult fill cleanups, the advanced wellbore cleanup tool variant helped in multiple polymer and sand fill environment cleanouts over various wells over conventional methods of cleanup.