Summary
With the development of more and more subsea fields, the challenge for
scale-inhibitor squeeze treatments is to reduce intervention frequency by
extending squeeze treatment lifetime while concomitantly reducing any potential
damage in both low water-cut and high water-cut wells. This paper
discusses the technical problems and examines new technologies for treatment of
such production wells through their life cycle. This paper covers the
findings from late 2001 through early 2002. Because even newer
technologies have been developed since the writing of this paper, it should be
read as the history of technological development.
Scale control technology available to control scale formation within the
reservoir and near-wellbore area of production wells will be outlined with a
focus on the current developing technology to control scale within low
water-cut wells. Moreover, this paper shows that the new technical area of
emulsion-scale-inhibitor-delivery systems, originally designed to control scale
within low water-cut wells, has applications in both low and high water-cut
wells.
This study assists in developing an understanding of the mechanism of
interaction of emulsion-based products—in particular, the impact of the level
of water saturation within the core system. In addition, it demonstrates
that the emulsion particles are retained in the core matrix during both crude
and brine flowback. This paper indicates that the emulsion product offers the
potential for extremely long squeeze lifetimes with minimal damage in
oil-production wells with rising water cut. It also demonstrates how
different technologies have their own place in the life cycle of a production
well.
Introduction
Flow assurance is an essential aspect of the economic production of crude
oil. It can be considered the ability to produce petroleum fluids economically
from the reservoir to a production facility over the lifetime of a field.
Scale control is one of the key aspects of the flow-assurance issue. The
increasing number of subsea fields, together with deepwater production, raises
particular issues and evolving challenges for flow assurance beyond those seen
for simple vertically drilled wells. The complexity of new well completions in
terms of horizontal and multilateral wells, subsea tiebacks, and commingled
flow presents particular challenges. Where scale-inhibitor treatments are
required for such complex wells, they are often associated with very high
intervention costs.
Scale control issues need to be addressed as part of asset life cycle
management, whereby the issues are tackled before field development/production
[i.e., capital expenditure (capex) phase] rather than being reactively
confronted once water breakthrough occurs [operational expenditure (opex)
phase]. Such an approach allows for the selection of an appropriate
economic technology. Indeed, the anticipated problems may influence the
plans to develop a field, for example, in terms of water-injection strategies
or implementing appropriate technology upon well completion.
Scale control within life cycle management is based on varying challenges
seen with the increase in water cut as a field and its wells move from dry
production to high water cuts. This is associated with four phases of
field development—project, plateau, decline, and decommission (Fig. 1). At the
project stage, scale control treatment strategies can be developed. The
scale issues at subsequent stages depend on the nature and severity of the
anticipated scale problem. Fig. 2 outlines the scale issues associated
with the injection of seawater into a reservoir with barium and bicarbonate
present in the formation water.
The process of evaluating the risk of scale in a field under appraisal is
briefly outlined below. The factors to be taken into account when
evaluating the risk of scale formation and control are described in detail,
along with currently available technologies and the gaps that exist in a recent
SPE publication (Jordan et al. 2001).
© 2006. Society of Petroleum Engineers
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History
- Original manuscript received:
24 August 2004
- Revised manuscript received:
6 June 2005
- Manuscript approved:
6 June 2005
- Version of record:
20 May 2006
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