In the Viking formation of the Southern North Sea, 20/40 ceramic with a dual resin coating was used to increase the productivity of a gas well from 8.5 mmcfd by over 5 fold to 43.5 mmcfd at reduced drawdown. Demonstrating higher productivity and minimal proppant flowback made this field economic.
This paper describes the implementation of a twin propped fracture stimulation treatment, carried out on the 49/17-12 exploration well of the Viking Wx structure, in the Southern North Sea (SNS). Initial appraisal of the potential field development was disappointing, the well flowing at a rate of only 8.5 MM.scf/d, indicating a field development to be uneconomic. Stimulation by a joint Conoco/BPX team, employing novel fracturing technology, provided dramatic increases in production to ca. 43.5 MM.scf/d with less applied drawdown. The design approaches employed during these treatments could have potential for widespread application to other SNS gas fields.
In this paper critical pre-treatment testing and reasoning behind operational decisions are discussed. In a companion paper the post stimulation rates/testing and well clean-up are described. Several key aspects of these treatments included: the use of two stacked fractures in order to successfully place proppant across the entire 830 ft reservoir section; the use of a Step Down Test (SDT) to identify the nature of high near wellbore pressure losses and subsequent removal using sand slugs; the use of a newly developed dual-coat partially curable Resin Coated Proppant (RCP) product, never previously utilised in the field, to minimise the opportunity for prolonged proppant back production and a seawater Mini-Frac to attempt to help identify the true in-situ permeability. Finally, the use of a Surface Read-Out (SRO) gauge enabled real-time decision making to optimise the treatment schedule.
Author(s): M. Rylance, BP Exploration; S. Haidar, HES; G. Sykes, CUKL; J. Pyecroft, HES
Paper Number: SPE 36472