No abstract

The UK Continental Shelf (UKCS) is one of the most mature offshore basins in the world. Achieving optimal recovery from the basin is demanding, but as the anticipated ultimate recovery factor is 46% (1) of oil initially in place, there is still significant opportunity to optimise recovery from the existing oil fields. PILOT, a partnership between the UK Oil and Gas industry and the UK Government, has been re-focussing its efforts on maximising North Sea recovery. There are currently only two Enhanced Oil Recovery (EOR) schemes operational within the UK North Sea. The principal barriers to implementing EOR projects are believed to be (1) incomplete subsurface understanding; (2) supply of secure, low cost injectants; (3) the challenge of implementing EOR retrospectively on a brownfield site; (4) concerns over project economics. The PILOT EOR Work Group was set up in 2012 to co-ordinate industry and government attempts to tackle these challenges. A three phase programme was identified to: (1) systematically screen the UKCS fields for EOR potential; (2) engage industry and look for synergies and collaborative opportunities to progress EOR understanding; (3) where possible, initiate new EOR projects with operators. The UKCS EOR screening exercise confirmed that there is still a significant realistically achievable EOR prize of up to 1 billion barrels of oil. The second phase of work focussed on developing collaborative ways of working to tackle the technical and commercial challenges associated with EOR projects, with particular focus on offshore ‘brownfield’ environments. Three EOR techniques were progressed and high graded on the basis of their prize and do-ability in an offshore environment: (a) Low Salinity Waterflood EOR; (b) Chemical EOR; (c) Miscible Gas Injection. Industry workshops were held for each EOR type and prioritised work programmes were implemented via operator "clusters", facilitated by the PILOT EOR Work Group. Examples of deliverables include (i) generation of a low salinity coreflood protocol to ensure that laboratory studies are performed in a consistent manner; (ii) initiation of a Joint Industry Project and an industry call for proposed facilities solutions for implementing low salinity on brownfield platforms; (iii) identification of industry resource to support UKCS operators with planning of chemical EOR opportunities. Successful completion of these collaborative activities will increase the chance of implementing further EOR schemes in the UKCS, unlocking the significant EOR prize.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOperators are always looking for ways to reduce risk in high cost environments and maximize value. Many challenges exist in the drilling environment today including depleted sands, lost circulation zones, weak formations and rubble zones. Casing and liner drilling has found its way from a niche market into the mainstream drilling environment through recent successes in a variety of these applications. There exist several options to drilling down casing or liners. These include retrievable BHA's with traditional measurement and logging equipment and non-retrievable BHA's that are drilled or reamed into place and cemented. This paper presents several case studies where non-retrievable casing/liner drilling technology has either improved the economics of a challenging application or made the application technically viable. These applications vary from onshore wells with tight fracture gradient schemes, shallow onshore wells looking to improve economics in surface hole intervals to offshore wells reducing risk by drilling or reaming down casing and liner strings. Applications will be taken from the Gulf of Mexico, South Texas, West Africa, Australia and Norway. The justification of using casing/liner drilling technology on these wells will be explored, as well as the lessons learned to apply to future drilling programs.

Parker et. al., (2015), SPE 175535, presented an engineered completion methodology utilizing diagnostic technology integration relating to horizontal shale wells in the Delaware basin. That paper focused on technologies pertaining to hydraulic fracture design for the Wolfcamp A reservoir using a discrete fracture network (DFN) model for predicting fracture geometry, formation evaluation, oil tracers, microseismic monitoring and production history matching. The final results of the paper showed that the application of an integrated technology approach provided the operator with a systematic method for designing, analyzing, and optimizing multi-stage/multi-cluster transverse hydraulic fractures in horizontal wellbores. Since publishing the paper, the completion and fracture stimulation design methodology has been further extended with improved well performance. This new work presents longer term well results from the original paper and additional wells that have since been completed with design improvements based on this process. Further technologies have since been added to the completion processes which have enhanced well performance, including the application of rate transient analysis (RTA) analysis, applied post job engineering analytics (APJA), additional pressure history matching (PHM) and post-fracture pressure matches to help refine the DFN model. The purpose of this work will be to further outline the benefits of utilizing multiple diagnostic technology integration to design, analyze and optimize completion and fracture stimulation design in the Wolfcamp shale. Detailed discussion related to created and propped fracture half-lengths, estimates of minimum conductivity, perforation design and cluster efficiency are presented. The value of diagnostic technology, EUR considerations and well economics will also be addressed. Readers of this paper will gain insight on how sound engineering, fracture modeling and data integration can increase recovery and optimize completions in the Wolfcamp and Bone Spring formations. Those working in the Delaware and Midland basins can readily apply specific learnings from this work to new completions. Additionally, the methods and engineering principles presented in this paper will provide a basis-of-design to enhance productivity and well economics for horizontal wells in unconventional resources.