Summary Kharyaginskoye field belongs to Pechora-Kolvinsky oil and gas bearing area of Timan-Pechora oil and gasbearing province. LLC Zarubezhneft-production Kharyaga exploits the following productive strata of the carbonate part of Kharyaginskoe field: Artinsky layer (P1ar) and Asselsky and Sakmar horizons (P1a + s) and the D3-III productive object associated with the upper Devonian, represented by sediments Zadonskogo-Yelets horizons. However, the main object in operation is the D3-III formation. The paper considers the complex process of designing acid treatment (AT), which includes physical and chemical studies of acid compositions (AC), formation fluids and object rocks, physical modeling of acid effects on the studied core samples, calculating the optimal AT design based on mathematical modeling. The formed approach allows you to determine to optimize the key parameters of the design of wells: the optimal concentration of the main hydrochloric acid in AC, volume, speed, number of stages of injection of AC and flow diverter, as well as calculate the predicted values of the parameters of the well operation after AT.

The development of carbonate reservoirs using peripheral and pattern water flooding typically achieves oil recovery factors ranging from 0.3 to 0.5, which is due to some complicating factors, such as, oil-wet surface of the pore space or the surface with intermediate type of wetting, unfavorable ratio of oil and water viscosities, presence of extensive structure of fractures, and significant variations of permeability down the reservoir section. In a complex geological environment, wells display abrupt fluctuations of water production that is an evidence of formation water being by no means the most efficient displacement agent. In these conditions, low-salinity water flooding can improve oil recovery. This paper reports on SCAL results of oil recovery factor determination and spontaneous imbibition using water with different composition and total solinity for Object 2 of Kharyaga oil field. Also, report contains design of on-site determination of residual oil saturation using Single Well Chemical Tracer test technology for evaluation of EOR efficiency. Laboratory tests showed, that low-salinity Jurassic water flooding with total salinity about 5 g/l could rase recovery factor up to 4% and also give incremental recovery due to effects of spontaneous imbibition for permability lower than 100 mD, which makes the injection of Jurassic water more preferable.

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A global trend to introduce enhanced oil recovery (EOR) methods at the early field development stages has been recently observed. Zarubezhneft group is no exception in this regard. Early introduction of EOR methods makes it possible to achieve higher process efficiency, and, first and foremost, economic efficiency. This article describes a pilot project involving implementation of diverter technologies at the field with complex carbonate reservoirs. The following aspects have been reviewed: the structure of the Kharyaga D3-III reservoir, main issues related to the reservoir development and ways to resolve such issues. Laboratory studies of the applied compositions’ properties, as well as filtration experiments have been described. The article also presents an overview of the available diverter technologies. The article also describes field implementation of the operations completed, namely, criteria for interface area selection, injection design development, work progress and efficiency evaluation for the EOR method applied. The operations completed on 5 injectors resulted in around 65 thousand tons of incremental oil from the producers. The operations were found successful; a new program for injection of polymer solution slugs is currently being developed.

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