Smiety of Petroleum Engineers. Ekctronb reprcduciion, distrtsition, or storsge of sny part of this paper for cwrnmem"sl PUPS without the kwitten mnsent of the Sceiety of Petroleum Engineets is prohibtied. Permission to reproduce in print is restricted to an abatrsct cf not more than WI words iluatrations may not be wpiad. The abstrsct must contdn conspicuous scknowfedgment of where and by whcm the paper ws presmtad. Wtite Librarian, SPE, P.O. Box 833835, Richardson, TX 75083-3336, U.S.A., fsx 01-972-952-9435. AbstractGoodwyn platform wells produce up to 220MMscf7d of raw gas yiel~ng UP to 20,000 bpd of stabilised condensate. The high productivity of the wells has reduced the number of development wells needed to satistJ platform capacity with significant cost savings. This high well capacity was achieved through the early recognition of the reservoir inflow potential in the completion design and addressing the critical issues of erosional velocity, Iifecycle sand production, sub-surface and surface equipment integrity in a high flow, high stress environment. To maximise the well potential the erosional limit was extended based upon actual experience. The risk of sand production was managed through a philosophy covering sand prediction and its control during operation. Well hardware was tightly specified and qualified within the defined operating envelope. These solutions were applied to both the initial conventional wells and for the later extended reach horizontal wells. Results fkom Goodwyn wells demonstrate that actual performance match the targeted ideal and that the issues have been managed. This paper presents a systems approach to well design where technical and external issues are taken into consideration. It is a retrospective look at the issues addressed for Goodwyn well desi~with updates to include current techniques.

This paper describes the design and qualification testing of high density oil based screen running fluids for an HPHT subsea gas field development in the Norwegian Sea. The field of interest contains gas bearing sandstones with permeabilities up to 5-10 Darcy buried at greater than 5000 m at high temperature and pressure (185 °C, 830 bar). The wells are designed to be completed with standalone screens. However, running screens in high density OBM has been a challenge for the industry due to the high solids load of such fluids. To qualify an HPHT screen running fluid, crucial to the economical development of this field, a rigorous fluid testing program was designed and carried out. The main drivers for the fluid qualification are to ensure that: The fluid is stable at downhole temperature to allow the running of the screens to bottom without plugging The fluid should remain mobile to allow easy backflow after a 28-day static period to allow subsequent well completion operations and back flow of the wells The fluid should not plug the screens after the 28-day static period The fluids were first designed and tested in vendor laboratories to ensure good long term stability and mobility. This was followed by internal confirmation testing by the operator. Final qualification at a third party facility for stability and mobility was carried out at simulated downhole conditions using a purpose built HPHT cell incorporating a sand control screen. The results of the qualification program showed that a 1.90 sg oil-based fluid containing fine barite can deliver a feasible solution to the completion challenges for the HPHT field development. The designed fluids are stable, easy to backflow and will not plug the sand control screens. The learnings from this study will also be presented.

Production and surveillance engineers need practical models to help balance out the reward of maximizing production and the risk of ramping-up the well too much that damages the completion. This paper presents a well flux surveillance method to monitor and ramp-up production for openhole stand-alone screen (OH-SAS) completion that optimizes production by considering risks of production impairment and screen erosion failure. The flux surveillance model for OH-SAS assumes the filter cake from drilling operations does not cleanup uniformly during fluids unloading and production. This leaves pinholes on the filter cake that cause concentrated flows. The flux model contains three components: (a) capture and describe input properties of pinhole, (b) link completion pressure drop of flows across filter cake region and through pinholes to surveillance results from pressure transient analyses, and (c) distribute fluxes in the SAS wellbore. The model uses three input parameters to describe the pinhole diameter and internal filter cake properties. They are determined as a system utilizing the laboratory return permeability test, computerized tomography scans of test samples, and computational fluid dynamics simulations. The completion pressure drop incorporates radial and hemispherical flows and captures the compounding skin effects of pinholes with internal filter cake. Flux distributions are modeled as a network system. This contains branches and nodes that incorporate radial and vertical flow resistances in the annular region of SAS. Application of filter cake properties and pressure transient analysis data showed the completion pressure drop as a function of flow rate is non-linear and higher with pinholes than without pinholes. By not incorporating pinholes in surveillance, operations can potentially limit ramp up when the completion pressure drop in the field is higher than predicted. Results from the network model showed the largest radial screen impingement velocity is at the top section of screen. The axial annular flow velocity or scouring velocity is two orders of magnitude larger than the screen impingement velocity. This warrants further considerations of wellbore enlargement and screen scouring erosion mechanisms due to the high axial annular flow.

Summary Well surveillance requires practical models to balance the reward of maximizing production with the risk of ramping up production too much, which damages the completion. In this paper we present a method to monitor and ramp up production for openhole standalone screen (OH-SAS) completion. The objective is to optimize production using pressure transient analyses to assess the completion impairment and failure risks during the production ramp-up process. The flux model incorporates filter-cake pinholes, which are formed from nonuniform deposition and cleanup of filter cake during drilling and completion operations. Pinholes cause concentrated fluxes and increase completion failure risks. The method comprises three components, which are (1) determine pinhole properties from laboratory tests, (2) relate completion pressure drop of production through pinholes to pressure transient analyses, and (3) distribute fluxes in the standalone screen wellbore. Examples are presented and show that the completion pressure drop as a function of flow rate is nonlinear and higher with pinholes than without pinholes. By not incorporating pinholes, operations can potentially limit ramp-up. Flux distribution examples show that the largest impingement or radial velocity is at the top section of screen. The axial annular flow velocity or scouring velocity is two orders of magnitude larger than the screen impingement velocity. An integrated flux surveillance method for OH-SAS completion is presented for field applications.