Summary
Oil productivity from Mumbai High field, an offshore multilayered carbonate
reservoir, increased significantly through the implementation of a major
redevelopment program. Geoscientific information available from approximately
700 exploratory and develop- ment wells drilled in the field during nearly 25
years was incorporated during geological and reservoir simulation modeling of
the field. High-technology drilling (viz. horizontal/multilaterals for the new
development wells) was adopted on field scale to effectively address typical
complexity of the layered carbonate reservoirs. Since the commencement of the
project in 2000, approximately 140 new wells were drilled, mostly with
horizontal and multilateral drainholes. Besides these, more than 70 suboptimal
producers were also converted as horizontal sidetracks under brownfield
development. The horizontal sidetracks were drilled as long-drift sidetrack
(LDST), extended-reach drilling (ERD), LDST-ERD, short-drift sidetrack (SDST),
and medium-radius drainhole (MRDH) types of wells through the application of
innovative and emerging drilling technologies with nondamaging drilling fluids,
whipstocks to kick off sidetrack wells, rotary-steering systems, and expandable
tubulars to complete horizontal sidetracks in lower layers. With the
implementation of this project, the declining trend was fully arrested and a
significant upward trend in production has been established.
Introduction
The field redevelopment process requires the intergration of
reservoir-development strategies, facility options, and drilling and production
philosophies to maximize oil and gas recovery from a matured field. A
significant number of case studies are available on mature field revitalization
using a multidisciplinary team concept, exhaustive geo-scientific data
analysis, and new drilling technologies (Chedid and Colmenares 2002; Clark et
al. 2000; Dollens et al. 1999; Kinchen et al. 2001). Advancements in drilling
and completion technology have enabled construction of horizontal wells with
longer wellbores, more-complex well geometry, and sophisticated completion
designs. Horizontal wells provide an effective method to produce bypassed oil
from matured fields. In the early 1980s, this technology was in the development
stage and was used in limited applications. By the 1990s, the technology had
matured, and its acceptance in the industry had increased significantly.
Performance of horizontal/multilateral wells, risk assessment of
horizontal-well productivity and comparison of horizontal- and vertical-well
performance in different fields is available in literature (Babu and Aziz 1989;
Brekke and Thompson 1996; Economides et al. 1989; Joshi 1987; Joshi and Ding
1995; Mukherjee and Economides 1991; Norris et al. 1991; Vij et al.
1998).
A significant number of horizontal/multilateral development wells were drilled
as a part of redevelopment of Mumbai High, a matured multilayered carbonate
offshore field in Western India. The details of new technologies applied and
performance of these new high-technology wells are presented in this paper.
Besides comparison of well productivity of horizontal and conventional
sidetrack wells, this paper presents some technical issues faced.
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
23 August 2005
- Meeting paper published:
4 December 2005
- Revised manuscript received:
3 January 2007
- Manuscript approved:
12 February 2007
- Version of record:
20 October 2007
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