The most efficient way of production enhancement is the hydraulic fracturing which has proven efficient in majority of the fields in Western Siberia and over the world. Despite wide stimulation experience in the Siberian region there are still some unresolved issues. One is the proppant flowback, a root cause of well equipment damage and also reduction in conductivity of the fracture itself. One of the ways to prevent the problem is the usage of resin-coated proppant (RCP). However there is a disadvantage of this method - agglomeration of polymeric material reduces fracture conductivity in the near-wellbore area. Since 2013 a pilot campaign with the usage of rod-shaped proppant has started in a region. This unique product has two main advantages over a classical spherical proppant: enhanced conductivity of a proppant pack and inherited proppant flow back prevention. Due to the rod-shaped form of the particles, pack has improved stability. Comparison of conductivity tests for different proppants shows that rod-shaped proppant outperforms conventional ones typically used in the region. This also leads to better fluid and polymer recovery and results in increased effective fracture length, hence in substantial production enhancement. There are 9 oil fields near Langepas a city in Khanty-Mansiysk district. These oil fields are at the latest stage of development: decreasing production rates and recovery of the most part of resources. Drilling has shifted to edge zones of the reservoirs and wells start-up is challenging due to low production rates (small net pays and low values of permeability and porosity). At the moment rod-shaped proppant has been successfully implemented in 4 wells on Jurassic and Achimov formation and the first positive results have been obtained - no proppant flow-backs detected and wells productivity enhanced by 20%. Detailed results of the first project with rod-shaped proppant application in Western Siberia (Russia), including a comprehensive analysis of well production performance, are covered in this paper.
Oil fields of the Samara region are at a late stage of development, which is reflected in declining of their production level and rapid growth of watercut. About 30% of the region's industrial hydrocarbon reserves are concentrated in carbonate reservoirs, which require stimulation. Low reservoir pressure, heterogeneity of the formation and the proximity of water-saturated interlayers significantly complicate the task of efficient field development and exploitation. In such conditions, the use of traditional methods for treating the bottomhole zone of carbonate rocks does not bring the expected results, and the worsening stock of exploited objects makes it necessary to look for new promising methods for increasing oil recovery. Carbonate reservoirs stimulation in the Samara region is carried out using a spectrum of various technologies of hydrochloric acid treatments, both to extend the life of old wells and to efficiently start new wells after drilling. In order to increase the effect from the performed hydrochloric acid treatments in 2016, the foam diverting technology was applied in the framework of pilot projects. This technology uses a stable non-damaging agent to form a nitrogen foam of 65% quality at the bottom hole. After the treatment, the foam breaks down into liquid and nitrogen, which in turn improves well flow back and helps to restore the natural flow. Despite the high degree of field development, the use of foam made it possible to achieve a 69% greater initial well productivity index than other methods. At the same time, the starting production rate of wells increased almost 2 times. The technology also allowed to reduce the specific volume of injected acid per meter of oil saturation by 25% without compromising the efficiency of the treatment, what has key importance from the point of view of economic feasibility. Based on the results of the performed pilot operations, nitrogen-foam acid treatments were included in the regular program of wells stimulation.
Paper describes in details a trial campaign with channel fracturing technique and it's positive effect on operational reliability and wells productivity that helped to revitalize brown Urevskoe oil field.Main challenges of the Jurassic formation are low permeability and high heterogeneity. Hydraulic fracturing is required for economic wells exploitation. Historically, hydraulic fracturing in oil fields close to the city of Langepas was developing towards aggressive designs with cleaner fractures, although increased risk of premature screenouts is encountered with such approach. To further improve efficiency and economics of stimulation treatments, a logical step in conductivity enhancement was made implementing channel fracturing technique. Channel fracturing allows for heterogeneous proppant placement leaving open channels inside proppant pack. Thus, conductivity of the system increases significantly. Channels also help to better clean out fracture from fluids and polymers increasing an effective fracture half-length, which is a goal in low-permeability formations. Another important advantage of the new technique is minimized risk of screenouts.Campaign was made implementing the technique to re-stimulate wells in brown Urevskoe oil field in Langepas area. Open channels showed reliable production increase from old wells in depleted regions. Proppant flowback is a common problem in such conditions and was encountered in many offset wells, therefore channel fracturing was enhanced by rod-shaped proppant at the tail-in stage. Such combination allowed preventing proppant flowback issues and improved conductivity in near-wellbore zone.Worldwide, this trial campaign is one of the pioneering re-stimulation projects implementing channel fracturing. Comprehensive analysis of performed operation, production comparative results and lessons learnt will make it possible to successfully extend the use of innovative technologies to many other brown fields that require stimulation.
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