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.
This abstract is submitted as an addendum to SPE-188853-MS, which deliberate about Improving Sweep Efficiency by Zonal Isolation Using High Expansion Ratio Inflatable Plugs. "M" field contains medium gravity viscous crude (10-20cp) in high permeability sands. Application of EOR technique is considered pivotal in sustaining the plateau production rate and maximizing the ultimate recovery from this field. "M" field is currently under polymer flooding with wells completed in a 5-spot pattern. The high viscosity crude in this field, with an unfavorable mobility-ratio with water, mandated the need to switch from water to polymer flooding. Even though good sweep improvement was observed in most of the patterns, a few pattern producers didn't respond to polymer flood as expected. They exhibited poor sweep efficiency which resulted in bypassed oil and early water/polymer breakthrough. The poor sweep efficiency adversely affects the project economics by reducing the Expected Ultimate Recovery (EUR) and increasing the opex associated with produced water handling. Paper SPE-188853-MS outlined how the installation of "high expansion ratio inflatable plugs" in the pattern producers, improved sweep efficiency. This paper adds further case studies to it, carrying forward the success of these Plugs. Moving onward the process of isolation based on detailed analysis of pattern flood producer wells which were shut-in, due to high water-cut and production handling constraints. Saturation log were carried out to locate the poorly swept sand zones. Also, since most of the wells are sub hydrostatic and exist on artificial lift. N2 assisted PLT were carried out to identify high water cut zones and accordingly zonal isolation of such high water cut zones were planned. Temporary isolation was required to accommodate plans for future ASP (Alkaline Surfactant Polymer) flooding. Both mechanical and chemical isolation methods were explored and accordingly well candidates were identified for each of the methods for isolation. Mechanical isolation methods are discussed in the paper (chemical isolation being discussed in a separate paper). Last paper gave insight about plug passing through a minimum ID of 2.3" and set in a 7" production casing. After this campaign, more candidates with plug setting section of 9-5/8" Casing & 4-1/2" Screens were selected. Plug setting with Coil Tubing & E-line were explored and executed. The jobs were successfully conducted in around 30 producer wells. The isolation resulted in a 3-4-fold increase in the instantaneous oil production with around 40% drop in produced water cut. This demonstrated how the treatments improved the selective drainage of the poorly swept sands by allowing preferential movement of flood front in these sands. To support selective treatment of injector wells for sweep bypassed oil sands, through tubing inflatable straddle packer acidization jobs are being planned to further increase the injection in poorly swept zones.
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