Enhancing the efficiency of hydraulic fracturing in mature fields

Background: In developing mature fields, the issue of technology efficacy is often raised in the context of constrained reservoirs, such as reservoirs with small interstices (barriers) bordering water- or gas-saturated reservoirs. The ability to effectively developing such reservoirs increases the production of current reserves and prolongs the "life" of the fields under development. This study presents the experience of Gazprom Neft Group in the development of terrigenous reservoirs, where there is a high risk of a fracture penetration into water- and gas-saturated intervals, by hydraulic fracturing. This experience can be taken as a basis for increasing the production of current reserves for some mature fields under similar geological conditions, where this problem is particularly acute and requires solutions that minimize risks.

Aim: Selecting the optimal technological approach to ensure the technical and economic viability of projects involving late-stage fields or assetswith with under- or overlying watered reservoirs.

Materials and methods: The materials address several technological trends, consisting of the completion specifics and the technological approach to hydraulic fracturing. As the main solution, a combination of low-viscosity fluids with a polymer concentration ranging from 2.8 to 3.2 kg/m³ in various executitions, 20/40 and 16/20 proppant fractions, as well as completion with a cemented equal-hole diameter tailpipe with burst port collar. The presented vision allows not only to significantly reduce the risks to fracture penetration in lower (upper) layers, but also allows, in cases of Screen Out, to perform clean out jobs without involving expensive Coil Tubing operations.

Findings: The implemented integrated solutions have proven their effectiveness at facilities with restrictions on fracture propagation in height. The use of low-viscosity liquids made it possible to reduce the increase in water saturation of products after stimulation, and design solutions reduced the costs associated with such as Screen Out.

Conclusion: The experience gained in applying new technological solutions to wells with a high risk of a fracture penetration into water- and gas-saturated intervals is quite successful, which confirmed by actual work and well analysis. Hydraulic fracturing on linear gel has a highly potential in the fields of Gazprom Neft Group and can be using on the similar formations.