Chen, Tao (Champion Technologies) | Heath, Stephen Mark (Champion Technologies) | Benvie, Ronald (Champion Technologies) | Chen, Ping (Champion Technologies Ltd.) | Montgomerie, Harry (Champion Technologies) | Hagen, Thomas Hille (Champion Technologies Ltd.)
The development of effective scale squeeze inhibitors in carbonate reservoirs is still a big challenge, especially with the increasing environmental constraints. For tight carbonate reservoirs, formation damage is one of the major considerations as it can be caused due to fines mobilization, carbonate reservoir dissolution and collapse, and scale inhibitor compatibility issues. For the development of any product for squeeze application, the product must also demonstrate good inhibition performance, long squeeze life and accurate residual analysis at low concentrations as well as being suitable for improved placement techniques if required.
Many scale inhibitors are either irreversibly retained in chalk reservoirs due to uncontrolled precipitation reactions or are poorly adsorbed with both processes resulting in short treatment lifetimes. Some new, readily detectable, polymeric scale inhibitor chemistry, containing a special functional amine group to have a good affinity to the chalk reservoir, was developed to provide a balance between irreversible and poor retention and thus provide effective squeeze life.
The results of a comprehensive testing program, including compatibility, formation dissolution, dynamic tubing blocking, static adsorption and core flood tests will be presented, that will highlight the design and development of a polymeric scale inhibitor suitable for tight carbonate reservoirs while meeting the environmental requirements for application in the UK and Scandinavia.
The new polymer has been shown to demonstrate excellent retention and release characteristics while also being non-damaging to carbonate reservoir material. The impact of calcium tolerance, pH and molecular chemistry will be discussed with regard to the design and performance of the new polymer when compared to some environmentally friendly phosphonate chemistry and other polymeric scale inhibitors.
This paper will demonstrate a logical design procedure to develop an environmentally acceptable polymeric scale inhibitor product whose chemistry has been optimised for squeeze application in tight carbonate reservoirs. In addition, discussions on the mechanisms of scale inhibitor retention and formation damage with regard to selection, design and optimization of suitable scale squeeze inhibitors in tight carbonate reservoirs will be addressed.
Heath, Stephen Mark (Champion Technologies) | Juliussen, Bjorn (Champion Technologies) | Chen, Ping (Champion Technologies Ltd.) | Chen, Tao (Champion Technologies) | Benvie, Ronald (Champion Technologies)
A common method to prevent scale forming in oil production wells is to inject scale inhibitor into the formation in so called squeeze treatments. Conventional scale inhibitor treatments with a brine pre-flush, main scale inhibitor pill and brine over flush stages are often not considered to be economically efficient as a large proportion of the scale inhibitor introduced into the squeeze treatment is returned almost immediately and therefore does not serve to provide long term scale protection.
Various techniques have been used successfully to increase the proportion of scale inhibitor retention in the well during squeeze treatments. For example, it has been reported previously in many papers where poly amino acids and poly quaternary amines have been injected into a well as part of the pre flush process and have significantly improved scale inhibitor retention and scale squeeze lifetimes. It has now been found that scale inhibitor treatment lifetimes can be improved by incorporating an ionic polymer such as a poly amino acid or poly quaternary amine in the over flush stage of the squeeze treatment. Indeed this method has been found to further extend the treatment lifetimes when combined with the same additives in the pre-flush stage of the scale squeeze treatment.
The new scale squeeze design technology can be considered very flexible as it can be applied with most scale inhibitor chemistries including both phosphonates and polymers with minimal formation damage potential compared to most precipitation scale squeeze treatments. It should be applicable over a wide temperature range from 30°C to 200°C and, in addition, the treatment strategy also lends itself to both aqueous and non-aqueous deployment and hybrid treatments and could provide extra protection against fines production in water sensitive wells depending upon the ionic polymer deployed. Initial field treatments have demonstrated the potential to extend treatment lifetimes by retaining up to 20 to 50% more useful chemical in the treatment reservoir.
This paper will highlight the proposed mechanisms of how the ionic polymer additives can improve squeeze treatment lifetimes as part of the over flush and will present field data for treatments on two wells in an HP/HT field at 165°C that demonstrated improved chemical retention and scale inhibitor returns compared to treatments without the ionic polymer additive in the over flush.
Benvie, Ronald (Champion Technologies) | Chen, Tao (Champion Technologies) | Heath, Stephen Mark (Champion Technologies) | Chen, Ping (Champion Technologies Ltd.) | Montgomerie, Harry (Champion Technologies) | Hagen, Thomas Hille (Champion Technologies Ltd.)
Dynamic scale loop tests are one of the major test methods used in the oilfield scale industry to evaluate the minimum inhibitor concentration (MIC) performance of scale inhibitors under laminar flow conditions. However, this laminar flow condition may not often be representative of field flow conditions especially around chokes, downhole safety valves and in wells with ESP and ICD completions where the flow is turbulent. Under these turbulent flow conditions the MIC derived by standard dynamic loop test may be too low to inhibit scale formation and very seldom has focus been placed on the effect of turbulence on MIC of scale inhibitors.
It is possible to modify existing dynamic scale loop equipment to achieve turbulent flow conditions. However, the turbulent flow conditions imparted by the higher flow rate and narrow test coils still cannot match the really high Reynolds numbers experienced in real field conditions so a different approach was adopted to more closely replicate field conditions. This consisted of installing an adjustable small bore valve in the dynamic loop rig which closely simulates the turbulent environment around chokes and downhole safety valves.
This new methodology and testing under turbulent and laminar conditions (at lower Reynolds numbers) was used to gain an understanding of the impact of flow on scale deposition and MIC and this information was used to design and identify new environmentally friendly P containing scale squeeze inhibitors that demonstrated excellent performance under turbulent flow conditions.
This paper will give a comprehensive study of the effect of flow condition on the scale formation and inhibition and, in addition, will detail how this methodology and new chemistry can be coupled to a chemical technology toolbox, that also implements techniques for advanced scale inhibitor analysis and improved scale inhibitor retention, to design optimum scale squeeze packages for harsh scaling conditions.
Thompson, Alan K. (Champion Technologies) | Heath, Stephen Mark (Champion Technologies) | Juliussen, Bjorn (Champion Technologies) | Gundersen, Thomas (Vitas as) | Andresen, Alf Terje (Vitas as) | Dahlgren, Per Anders (Vitas as)
The individual analysis of polymeric scale inhibitors in co-mingled flow backs from wells in subsea and deepwater templates is a particularly challenging application for analytical techniques in the industry.
The application of the analytical technique of mass spectrometry to this challenge has resulted in routine 3rd generational analytical methods where a primary inhibitor can be quantified in the presence of a secondary subsea squeeze inhibitor and a tertiary topside scale inhibitor; something which had not been demonstrated previously in commercial applications. In more complex deep water field developments in the North Sea and Gulf of Mexico, where 4-8 wells can be co-mingled, the use of these third generation analytical techniques may not always be sufficient therefore it is necessary to develop improved methodologies to cope with the presence of an increasing number of chemical families.
This paper presents details of an emerging 4th generation analytical method which is being developed to allow the accurate quantification of 4-5 chemical families of scale inhibiting polymers in the presence of each other and other production chemicals such as corrosion and hydrate inhibitors. These would include scale squeeze polymers, scale inhibiting polymers applied subsea, or scale inhibiting polymers applied topsides. This method builds upon the 3rd generation analytical technology by using a novel mass detection technique which gives a much enhanced sensitivity and specificity to molecular functional groups.
The development of this method will add to the rich "toolbox?? of state-of-the-art analytical techniques which now allow the analyst an unparalleled ability to generate accurate, specific and robust data from even the most demanding of applications and allow the chemical supplier and operator to individually monitor wells tied back to even the most complex of subsea templates in the most challenging of deepwater applications.
Chen, Tao (Champion Technologies) | Benvie, Ronald (Champion Technologies) | Heath, Stephen Mark (Champion Technologies) | Chen, Ping (Champion Technologies Ltd.) | Hagen, Thomas Hille (Champion Technologies) | Montgomerie, Harry
A tight carbonate reservoir is one of the typical formations in the oil and gaswells. The unique feature of the subject reservoir is low permeability (2-5md). The formation damage, compatibility, residual analysis and squeeze lifeare still major challenges for the conventional scale inhibitor squeezetreatment in this kind of reservoir.
The development of effective squeeze scale inhibitors to prevent the aboveproblems in BaSO4 scale scenario is still a big challenge, especially with theincreasing environmental constraints. For tight carbonate reservoirs, theformation damage is one of the major considerations since the formation damagecan be caused due to fines mobilization, carbonate reservoir dissolution andcompatibility issues. For the development of any product for squeezeapplication, the product must also demonstrate good performance on field scaleinhibition, long squeeze life and accurate residual analysis at lowconcentration.
This paper will demonstrate a logical design procedure to develop anenvironmental friendly polymer scale inhibitor product suitable for challengingtight carbonate reservoir through squeeze application and will discuss themechanism of scale inhibitor retention with regard to selection and design ofsuitable scale squeeze inhibitors.
Many scale inhibitors are either irreversibly retained in chalk reservoirs dueto uncontrolled precipitation reactions or are poorly adsorbed with bothprocesses resulting in short treatment lifetimes. A new polymeric scaleinhibitor chemistry, containing a special functional amine group to have a goodaffinity to the chalk reservoir, was developed to provide a balance betweenirreversible and poor retention and thus provide effective squeeze life. Theresults of a comprehensive testing program, including compatibility, formationdissolution, dynamic tubing blocking, static adsorption and core flood testswill be presented, that will highlight the development of polymer scaleinhibitor suitable for the tight carbonate reservoir, while meeting theenvironmental requirements for application in the UK and Scandinavia. Inaddition, a new residual detection method will be presented which willdemonstrate accurate scale inhibitor detection at low concentration (<1ppm)in high TDS water.