No abstract

Waterflood is most commonly used secondary recovery mechanism in conventional sanstone reservoirs worldwide. Waterflooding assists in pressure maintenance and increases the field estimated ultimate recovery (EUR). Conformance in water injector wells plays an important role during waterflooding of a reservoir. Better conformance results in improved vertical sweep efficiency leading to higher recovery. Continuous injection of fluids into the reservoir at higher rates may create channels for preferential flow. Zones of higher permeability, leading to higher injectivity in selective zones, can also exist because of various lithological conditions and rock structures comprising of naturally occurring fractures or fissures. For injection wells, the entry of fluids into a set of perforations is governed by the quality of the perforations and the permeability of the formation at that depth. Preferential flow of injected fluids into selective pay intervals results in diminished overall sweep efficiency. (J. Vasquez, et.al., 2008). This paper discusses the use of thermally activated gels from polyacrylamides and metal chelates applied for selective reservoir matrix permeability reduction in an injector well. A low concentration, low viscosity delayed crosslinker gel system employing partially hydrolyzed polyacrylamide (PHPA) exhibiting 12-14% degree of hydrolysis level with chromium acetate as crosslinker offering delayed gelation time was used to selectively isolate one of the payzones. A non-profile retrievable (NPR) plug was installed to isolate the target interval from the rest of the pay zones to enable selective treatment of the interval using coiled tubing (CT). The fluid was customized to minimize CT friction while ensuring that the rheological properties of the fluid in the reservoir would achieve the desired diversion and allow delayed gel crosslinking mechanism assuring avoiding of gel crosslinking in CT while pumping in progress. Denser brine relative to the delayed gel density was spotted above the NPR plug to avoid gel settling on the plug for easy retrieval of the plug post-treatment. Injectivity was measured and subsequently, the treatment was placed as per design while constantly monitoring the pressures so as to qualitatively determine the effectiveness of the treatment placement. The treatment resulted in significant alteration in injectivity of the targeted zone. Post-treatment production logs confirmed an improvement in the injection conformance. Later, the zone was isolated and the bottommost zones were selectively stimulated enhancing the injection and thus improving sweep efficiency. Since the crosslinked gel system is not prone to any disintegration when in contact with acidic interventions, the treatment ensures a superior longevity of the conformance control when compared to other conventional diversion or zonal shut-off treatments. The success of the treatment substantiates that the CT deployed low viscosity, low concentration delayed crosslinked gel system application can be successfully extended to selective water shut-off applications in producer wells. The injector profile modification treatment executed offered a comprehensive solution to conformance issues enhancing volumetric sweep efficiency, pressure maintenance across depleted sands and avoiding further water cycling in producer wells.

The restoration of rivers is an essential component of sustainable development, which has as its dual goals the reduction of environmental deterioration and the enhancement of societal well-being. This research paper examines the case of the Dravyavati River revitalization project in India, focusing on the evaluation of its ecological and social dimensions and its contribution to sustainability. The Dravyavati River, which flows through Rajasthan, was subjected to significant pollution and deterioration as a result of urbanisation and industrial operations. The project aimed to improve the biological state of the river, as well as the quality of the water and the public space that was available to the towns that were located in the area.

A significant part of multimedia data to be transmitted over the network consists of image data. In this paper,a cellular automata based image encryption algorithm which functions as a stream cipher has been presented. This encryption algorithm is specifically intended towards encrypting the image data. Proposed image encryption algorithm uses a hybrid cellular automata to produce a random key-stream while AES-key expansion module infuses the reasonable security in the image encryption system.

Cairn Oil and Gas operates the M field in the Rajasthan block along with its JV partners. The M field is the largest onshore hydrocarbon find in India in the last two decades. The 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. Field M is currently under polymer flooding with wells completed in a 5-spot pattern. The high viscosity crude in this field, with an unfavourable mobility-ratio with water, mandated the need to switch from water to polymer flooding. Though good sweep improvement was observed in the majority 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. This paper outlines how the installation of "high expansion ratio inflatable plugs" in the pattern producers, improved sweep efficiency. A detailed analysis of pattern flood was undertaken to identify producer wells which were shut-in, due to high water-cut and production handling constraints. Saturation logs were carried out to locate the poorly swept sand packages. Temporary isolation was required to accommodate plans for future ASP flooding. Both mechanical and chemical isolation methods were explored. The mechanical method was selected because of its higher success rate in achieving a perfect isolation compared to chemical methods. An additional concern with chemical isolation treatments was the inherent risk of permanently damaging the formation. The existing completion design required the isolation plug to pass through a minimum ID of 2.3" and set in a 7" production casing. For this reason, high expansion ratio retrievable inflatable plugs were proposed. The waxy nature of the reservoir fluid mandated the use of Coil Tubing (CT) as the plugs required a clean fluid environment for expansion. The jobs were successfully conducted and the zones were selectively isolated in two producer wells. The isolation resulted in a fourfold increase in the instantaneous oil production of these wells with an associated drop in produced water cut. Production logs in the associated pattern injectors showed increased injection in the zones which previously had been poorly swept. This demonstrated how the treatments improved the selective drainage of the poorly swept sands by allowing preferential movement of flood front in these sands. The intervention helped the operator selectively produce from the poorly swept zones without the requirement of a major workover operation. Based on the success of the pilot project, the technique will be deployed in all applicable 7" cased wells. Its use in 9-5/8" cased wells is being investigated. Learning and information shared in this paper will be useful to anyone interested in using high expansion ratio plugs for wellbore isolation treatments.