Purpose. More efficient production of hydrocarbons from weakly consolidated sandstone reservoirs using improved method. Modification of the equipment according to the geological characteristics of the reservoir and the mode of production.Methods. Perforation is performed with two different types of charges (DP & BH), after that the modified gravel pack equipment is run in hole.Findings. The combination of double perforation and the application of modified gravel pack allows for more efficient hydrocarbons production from weakly consolidated reservoir without occurrence of sand in the flow, thus extending the production life of the oil and gas field with this type of problem in production.Originality. Application of improved method in hydrocarbon production from weakly consolidated reservoirs, which has shown improvement of production parameters. Practical implications.The technical and economic indicators of this method show the feasibility of its application to weakly consolidated reservoirs, allowing higher production of wells, thereby increasing the profitability of the field, and thus its lifetime. It is applicable to all weakly consolidated reservoirs, with proper design of gravel pack and analysis of geological properties of reservoirs.

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Risk and financial cost management are becoming increasingly important in the oil industry, especially in companies that have mature oil fields as assets. In such cases, risk and cost analysis are crucial to their existence. The paper analyzes the risks and costs through the modification of geological probability of success (POS) and obtaining the cost correction coefficient when planning capital investments in injection wells. Mature oil field “B” in the northern part of the Republic of Croatia was analyzed. For field “B”, these values were calculated: 0.8577 for probability of success for workovers, 0.4824 for modified POS for reservoir flooding, and 1.30 for cost correction coefficient for workovers.