Gravel-pack damage removal in horizontal and vertical wells
Abstract: This paper was prepared for presentation at the 1999 SPE European Formation Damage Conference held in The Hague, The Netherlands, 31 May–1 June 1999.
Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
Cited by 8 publications
References 8 publications
The Heidrun field located in the Norwegian Sea is an oil and gas producing field which has been developed with a tension leg platform (TLP) installed over a template with 56 slots. Two subsea production templates and three subsea water injection templates are also tied back to the TLP. All wells require sand control measures in the reservoir section to prevent sand production. The sand control philosophy has gradually evolved from cased hole gravel packs, through stand alone screens to todays preferred option of openhole gravel packing. Sand control in the field is challenging with high fines content in the reservoir and a potential for plugging from scaling from secondary recovery with seawater. Sand control integrity has failed in some wells and offtake rates in these wells are limited to Maximum Sand Free Rates (MSFR). In some cases intervention is required for remedial sand control or new sidetracks are planned. However, for a number of suitable wells, chemical treatments that consolidate the near wellbore area can be a viable alternative to improve well offtake rates.The chemical treatment is mixed in diesel and bullheaded in the well. The active chemical will react with the connate water in the near wellbore area and form a polymerized network which binds the sand grains together. In that way, the residual strength of the formation is increased and can withstand larger hydrodynamic forces before the grains are transported into the wellbore.To date three Heidrun wells have been treated with the sand consolidating chemical that has been developed in-house. Two of these are platform wells and the third is subsea. One of the platform wells has been retreated twice following a successful first treatment. This work describes the five different treatments; the planning, the execution and the post-job analysis. One of the treatments was not successful, another one was very successful. The reasons behind these results will be discussed. The Heidrun FieldThe Heidrun field is located in the Norwegian Sea in the Haltenbanken Area, north-west of the city of Trondheim. The field was discovered in 1985 by Conoco. In the development phase, Conoco was the operator, whereas StatoilHydro is the operator in the production phase. At production start in October 1995, ten wells were pre-drilled and completed; nine producers and one gas injection well. During the early years, oil was produced from the Fangst / Upper Tilje reservoir. In 1998 production from Lower Tilje / Åre was phased in. The TLP is anchored to the seabed at 350 meter depth. The platform has a three stage separation and no storage capacity. Oil is produced directly to oil tankers. In 1997 Heidrun started to export gas through the Haltenpipe. Today gas is also exported through the Åsgard Transport pipeline.
The Heidrun field located in the Norwegian Sea is an oil and gas producing field which has been developed with a tension leg platform (TLP) installed over a template with 56 slots. Two subsea production templates and three subsea water injection templates are also tied back to the TLP. All wells require sand control measures in the reservoir section to prevent sand production. The sand control philosophy has gradually evolved from cased hole gravel packs, through stand alone screens to todays preferred option of openhole gravel packing. Sand control in the field is challenging with high fines content in the reservoir and a potential for plugging from scaling from secondary recovery with seawater. Sand control integrity has failed in some wells and offtake rates in these wells are limited to Maximum Sand Free Rates (MSFR). In some cases intervention is required for remedial sand control or new sidetracks are planned. However, for a number of suitable wells, chemical treatments that consolidate the near wellbore area can be a viable alternative to improve well offtake rates.The chemical treatment is mixed in diesel and bullheaded in the well. The active chemical will react with the connate water in the near wellbore area and form a polymerized network which binds the sand grains together. In that way, the residual strength of the formation is increased and can withstand larger hydrodynamic forces before the grains are transported into the wellbore.To date three Heidrun wells have been treated with the sand consolidating chemical that has been developed in-house. Two of these are platform wells and the third is subsea. One of the platform wells has been retreated twice following a successful first treatment. This work describes the five different treatments; the planning, the execution and the post-job analysis. One of the treatments was not successful, another one was very successful. The reasons behind these results will be discussed. The Heidrun FieldThe Heidrun field is located in the Norwegian Sea in the Haltenbanken Area, north-west of the city of Trondheim. The field was discovered in 1985 by Conoco. In the development phase, Conoco was the operator, whereas StatoilHydro is the operator in the production phase. At production start in October 1995, ten wells were pre-drilled and completed; nine producers and one gas injection well. During the early years, oil was produced from the Fangst / Upper Tilje reservoir. In 1998 production from Lower Tilje / Åre was phased in. The TLP is anchored to the seabed at 350 meter depth. The platform has a three stage separation and no storage capacity. Oil is produced directly to oil tankers. In 1997 Heidrun started to export gas through the Haltenpipe. Today gas is also exported through the Åsgard Transport pipeline.
The further development of the Statfjord field for the Late Life pressure blowdown phase requires the drilling and completion of many infill wells from existing slots. The overall objective of these wells is to maximize oil production in the short term whilst securing future gas delivery potential for the late life phase. Well design to meet this objective is challenging. The Statfjord and Brent formations are sand prone and robust mechanical sand control completions are required in order to secure offtake rates during late life production. Also, after 28 years of production and water injection, the drilling and completion of wells through the differentially depleted formations is challenging due to a narrow pore pressure/fracture pressure window. Furthermore, the reservoir formations are substantially interlayered with shale sections and this meant that wellbore stability issues would pose significant challenges.Initial Late-Life well designs were based on drilling long open hole sections with an oil-based drilling mud providing low Equivalent Circulating Density (ECD), displacing the well to brine, and then running sand screens and performing an open hole gravel pack (OHGP) across the reservoir section with a conventional water pack. During the last three and a half years 27 Late-Life producers have been drilled and completed. This paper summarizes the operator's experiences over this period with emphasis on well design, drilling and completion tools, well fluid technology and well productivity. It explains how ambitions and well design had to be reassesed in order to overcome several challenges with the selected drilling and completion strategy.
In fields where it is unattractive to control barite scaling through chemical intervention (e.g. scale inhibitor squeeze treatments), one option is to substitute the injection of seawater with low-sulphate seawater (LSSW) for pressure maintenance. Injecting LSSW minimises the operational risk of barite deposition on injection water breakthrough. The specification for the LSSW sulphate ion concentration dictates the design of the Sulphate Removal Plant (SRP) required and may influence the field development strategy. There is the possibility that barite deposition can occur within gravel packs designed to minimise sand production. It is in these that the potential for scaling was investigated.Dynamic scaling runs were performed in laboratory scale gravel packs using a mixture of a Formation Water (FW) and LSSW. The initial design involved varying the total flow rates and mixing ratio of the brines in order to produce a 'safe envelope' (Ba 2+ /SO 4 2composition) that could be used in the field. The experimental procedure was developed to examine the steady-state effluent profiles and to use these to derive the rate constant, k, for barite deposition. This could then be used in a computer model to predict scaling quantities and timescales.Under 'true' LSSW conditions (20ppm sulphate) the steady-state effluent results proved difficult to interpret due to the limits of accuracy. The sulphate levels were then varied in order to increase the level of accuracy, with the hypothesis that, for a given set of conditions (temperature and pressure), the rate "constant" should remain the same for any Saturation Ratio (SR).Upon closer inspection of the derived rate constants, it was discovered that they were not constant but were directly proportional to the SR for the different input concentrations. Plotting the rate constants against SR showed a linear relationship between the two variables. This was confirmed by using sulphate and barium levels that were unrelated to the previous series of tests.The experimental procedure and the resulting model being developed from the work reported in this paper will assist in designing operational procedures to minimise rate related scaling in gravel packs in fields where squeezing is undesirable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
Contact Info
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Product
Resources
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.
