abou sayed

Dr Ahmed S Abou-Sayed left BPExploration in 1999 to establish

Advantek International, a consultingfirm based in Houston, Texas. He

holds advanced engineering degreesand has over 25 years of

experience within the petroleumindustry covering technology

development, management andtechnical consultancy. His work has

focused within the areas of wellintegrity, well stimulation,production and reservoir

geomechanics and environmentalcompliance, where he has beenextensively involved in producedwater management and oil field

waste disposal. He holds sixindustrial patents and has authoredand co-authored over 90 technicalpublications. Throughout his career,he has chaired and participated in

numerous steering andimplementation committees, served

on the editorial board of twoscientific journals and received

several achievement awards.

a report by

D r A hmed S A b ou - S a y e d

Production optimisation and improving a project’snet present value (NPV) for global hydrocarbonproducers need strategies for produced watermanagement (PWM), in order to eliminatesignificant economic and environmental barriers.PWM issues hamper production by restrictingadditional development or adding costs (US$0.15 toUS$2.50/barrel of oil (BoO)). Operators raise theeconomic limit for well operability or abandonexisting wells, while substantial recoverable reservesremain in situ. PWM poses the biggest challenge, yetoffers considerable benefits to brownfield operators.

While operators around the globe experienceidentical problems, local conditions andrequirements dictate that solutions are region-specific. Regions can vary significantly andboundaries may be set geologically, geographically orpolitically. An obvious example is PMW in offshoredeepwater conditions in contrast to onshore and/orthe Arctic or other sensitive areas.

PWM issues are multi-faceted. In many cases, theoverall solution may require several separate stepsfor complete resolution (reduction, chemicalremoval, profile control, separation, treatment,disposal and waterflooding use, etc.). Hence, twodominating themes emerge from the stakeholders’point of view: the need for holistic PWM and theabsence of ‘silver bullets’.

Operators should follow the UN waste managementpriorities/hierarchy framework. Principally, PWMmust aim to:

• reduce (water shut-off, downhole separation andreinjection, minimise chemicals);

• reuse (treat, irrigations and industrial uses);• re-form;• recycle (waterflooding); and• replace (injection).

Key factors in framing PWM strategies include thecompany’s internal and external environments (seeTable 1) and its technology and business drivers.Emerging trends establish an environmentally-friendly PWM position which comprises one of the

following declared policies:

• a move towards zero emission;• no discharge to surface or seas;• waste-to-value conversion;• incremental and progressive separation; and• pro-activity to influence partners, regulators and

environmental laws.

PWM strategies must be tooled in a technicalapproach to addresses production, separation anddisposal/injection operational segments of waterinjection and waterflooding. Management mustprovide the basis for selection of PWM strategycomponents and steer actions to increase revenueand lower project cost with no harm to theenvironment. Best practices must be based on resultsof comprehensive assessments of current PWM toolsand insights gained from industry projects.

Produced water re-injection (PWRI) for water-flooding/disposal is an increasingly important strategytoward converting waste to value and preserving theenvironment’s integrity during exploration andproduction (E&P) operations. Best practices andlessons learned for injector design, operation,monitoring, assessment and intervention provide costminimisations and efficient, green operations.

Facility and subsurface engineering are linkedthrough produced water (PW) quality targets,pumping needs, injector completions and facilityconstraints. Field cases and data mining will showthe wide variation in injector responses and underline the basis for performance. Fieldevidence indicates that injectivities can suffersignificantly in matrix injection schemes despite theinjection of clean water. Alternatively, injectivitymaintenance, when injecting untreated PW, isfeasible and practical.

The majority of injectors appear to be fractured.Fracturing has a major impact on facilities’statement of requirements (SOR), injectorcompletion, sweep and vertical conformance.Fracture propagation during seawater and PWinjection impacts injector performance. Models

Produced Water Management S t ra tegy – Sav ing the Asse t f rom Drowning in Produced Water

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depicting formation and fracture plugging, verticalwater partitioning and well testing exist. Bestpractices provide a positive impact on the overallinjection strategy. These effective, field proventools used to assess/quantify these issues are derivedfrom a decade-long PWRI joint industry project(JIP) that addresses water injection design andanalysis. Establishing how the engineer quantifiesthe impact on flood and well performance will bepresented along with field cases illustrating thedecision-making process.

Wat e r M an a g emen t B e n e f i t s

Produced water, which surfaces during oilproduction, typically contains hydrocarbons,naturally occurring radioactive material (NORM),production chemicals, solids and inorganic andmetal salts. In early stages, water may only be aminor component of produced fluids. As thereservoir depletes, PW volume increases. Watermay be injected to maintain pressure and sustainexisting production rates, but may be subsequentlyrecovered as PW. An example in the North Sea isthe approximate 1:1.5 oil-to-PW ratio. The averageoil-to-water ratio over a well’s lifespan is 1:6. Waterproduction for a gas platform runs 2m3 to 30m3 perday in comparison with 2,400m3 to 40,000m3/day

for oil producers. When it becomes economicallyunfeasible to treat PW, the operation is halted andthe remaining oil is abandoned. It is unknown ifthis fact is considered when regulators formulatetreatment standards for water disposal.

Increasing oil production, lowering costs forchemical and corrosion treatments, reducing capitalexpenditures and well intervention are parts of arational water management policy. ‘Greener’operations and regulatory compliance protect alicense to operate. Companies establish central watermanagement groups to increase capital expenditure(CAPEX) efficiency, reduce operating expenditure(OPEX) and improve environmental image.

ChevronTexaco’s (CVX) Kern River field is anexample of this trend. CVX earned revenue by sellingcleaned PW from this thermal recovery project forlocal irrigation. Petroleum Development in Oman(PDO) re-used water for irrigation and transportedthe excess to waterflood another reservoir, therebyprotecting local resources. These successes directlyresulted from focused management and use oftechnological innovations.

PWRI JIPs and industry alliances (supported byMobil, BP, Texaco and Chevron (MoBPTeCh))are examples of how industry groups collaborate on


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T a b l e 1

InternallyOperating companies have unique characteristics. The business scope, scale, human and intellectualcapital can be leveraged by information technology to improve business performance throughknowledge management, shared data and an open business model.

ExternallyThe environment is framed by service sector ability to deliver new technology and by vendorrelationships. Understanding the tension existing between vendor deliveries to operating companiescompared with smaller operators (striper wells) is important in setting a strategy for best practices.

Implementation of novel technologyImplementation of novel technology or process to operate within best practice paradigms is improvedthrough multilateral ventures between vendors and operators (e.g., produced water re-injection(PWRI) joint industry projects (JIP) and downhole oil–water separation (DHOWS) consortia). Bothsides (operators and service companies) have maintained competitive advantage through internaldevelopment and bilateral ventures with each other. Recent industry consolidation and oil pricevolatility creates an environment where vendor innovation and risk can be enhanced by proactivemultilateral ventures.

The vendor relationshipThis is that of a service provider. The core skill of any operating company is operatorship. This mayappear an outdated concept, but is valid as long as the operator assumes the financial, technical andcontractual risk. Effective relationships to guide, provide feedback and directly assist vendors tointegrate best practices can improve service delivery.

PWM. The UN’s Waste Management TechnicalMeetings, the EEC’s Convention for the Protectionof the Marine Environment of the North-EastAtlantic (OSPAR) convention, US NationalLaboratories and non-governmental organisations(NGOs) such as the Gas Research Institute (GRI)fund support for technical development.

R e g u l a t o r y F r amewo r k

Discharge restrictions for PW in offshore fields arecommonly implemented through MineralsManagement Service (MMS) and US EnvironmentalProtection Agency (EPA) regulations. In worldwidepractice, a prescribed range of standards ranges from10mg to 50mg/l total petroleum hydrocarbons withexceptions reaching to 100mg/l (regional andnational standards are sometimes expressed as amonthly average, as a maximum level or as both).

To date, emphasis has been placed on regulating theconcentration of oil in PW with its determined valuedependant on the analytical method used. In somejurisdictions, constraints are also imposed on:

• total dissolved solid concentration (TDS);• total suspended solid concentration (TSS);• copper, arsenic and zinc concentrations;• aromatic fraction;• concentration of specific radioisotopes; and• chronic toxicity of the whole effluent.

Suggested approaches for devising PWM strategiesinclude various options for advancing water manage-ment technology within operating companies andvary regionally depending on the organisation and thebusiness. Generally, there are four major elements toeffectively managing PW:

• Compliance with environmental standards (legalor best-practice based) is the most criticaloperational issue associated with PWM. Acompliance failure jeopardises a company’slicense to operate in a particular area.Compliance risks are mitigated with proactiveregulatory involvement, technology applicationsand knowledge management.

• Government agencies set regulatory standardsthrough consultation with operators andcontractors. Proactive participation by operatorsin regulatory forums assures their contribution tocreating solutions and provides insight toregulatory direction and emerging issues.

• The application of technology avoids potentialPW issues. Early application of new technologymay provide a short-term, competitiveadvantage. By combining dedicated, internal

resources for its application, new technology isbest utilised by active participation in industryjoint ventures. The specific areas applicable toPW include non-conventional well completionand intervention, smart wells, electricsubmersible pumps and designer chemicals (seeTable 2).

• The implementation of a knowledge management(KM) programme facilitates internal access, learningand application of best practices. In this context,KM is useful in increasing the reliability and qualityof vendor-supplied products and services.

P r o du c e d Wa t e r M an a g emen t

Maximum impact reduction on the environmentrequires the optimal utilisation of existing technologyand resources and a complete knowledge of theproduction process. In addition, careful managementof PW waste streams both on- and offshore and thereduction of contaminant in and the volume (re-injection) of discharged water into the environmentare goals of integrated PWM. This practice generallyfollows this series of steps:

• selection of the least hazardous chemicals in orderto minimise PW toxicity;

• reduction in the volume of water produced;• reuse of PW, if water quality allows (e.g., re-

injection for pressure maintenance);• reduction in the volume of PW to the ambient

environment; and• reduction in pollutant concentrations of

discharged PW.

Reduction in the volume of water produced at thewellhead may be achieved by profile modification,which includes:

• shutting down water producing wells;

• isolating water producing zones in reservoir bysetting plugs and using cement and chemicaltreatments;

• utilising polymer gels and relative permeabilitymodifiers;

• downhole separation; and

• use of hydro-cyclone separation followed bypumping oil to the surface and PWRI downholeusing submersible pumps

Reduction in the volume of PW discharged intoambient environments is minimised by reducing thewater at the wellhead. PWRI into undergroundformations (reservoir or unusable aquifers) presents abest practice approach. PWRI offshore has become


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everyday practice in brownfields. Higher organicmatter content of PW leads to increased potentialfor plugging. PW is often warmer than seawater,which results in lower fracture volumes in theformation and leads to a decreased injection rate.These limitations are overcome with newtechnologies and adoption of best practices.Reduction of pollutant concentrations in dischargedproduced water can result from these end-of-pipetreatment technologies:

• primary treatment equipment (e.g. skimmers) toprotect downstream facilities from surges andupset conditions;

• secondary treatment equipment (e.g. coalescersand flotation units) used for the removal of smalldroplets to bulk oil; and

• polishing treatment equipment (e.g. filters,hydrocyclones, stripping and filtration) to removevery fine oil particles.

Several other technologies have been developed for use onshore. The potential application for thesetechniques in offshore operations continues toevolve. Specific limitations such as space constraints,highly variable water flow rates, corrosive andscaling properties of the waste streams, extendedretention times, tendency to block, and high energyrequirements, impose severe restraints on theiroffshore utilisation.

Issue-specific techniques meet specific conditionsregarding dispersion droplet sizes, solids, quantity,energy consumption and size and weight of equipment.

It is crucial to initially define which components ofthe PW have a significant impact on ambientconditions prior to devising a PWM strategy.Maximum reduction in environmental risk frominvestment in treatment technologies is thenrealised. Results vary depending on field andproduction stages. In some cases, adjusting andoptimising the use of existing platform facilities andinstallations is sufficient. The choice of technologyand the implementation of best practices should bebased on an integrated evaluation. The evaluationof cost-effectiveness, in terms of implementationcost for a technology or practice versus theexpected environmental and economic riskreduction, is advisable. This approach avoidsimplementation of costly practices in situationswhere environmental improvement is not expected.

Integrated planning and PW and reservoirmanagement are required for new field development.Prior to introducing new techniques, existingdischarges must be examined. Where possible, impactassessments should be carried out on a regional basisrather than ‘installation-by-installation’. The basis ofenvironmental standards should be provenenvironmental impacts of E&P activities in thespecific areas with the consideration of regionaleconomic and environmental sensitivities.

Table 2

Produced Water Spectrum Production Separation Disposal/Injection

Operation elements Strategy and tactics Strategy and tactics Strategy and tactics

Injection wells Chemicals treatment Disposal

Production wells Gravity separation Reinjection

Development drilling Hydrocyclones Unconsolidated sands

Improved oil recovery Gas flotation Stimulation

Evolving technology Centrifuges Novel approaches

Reliability and quality Filtration Best practices

Evolving technology Knowledge management

Specific topics Best practices – compile the current lessons learned, successes and failures

(To each operational Operational trends – project expected trends and directional changes

element) Technology trends – current focus areas, barriers and possible breakthroughs

Filed specific – examples

Business issues – main drivers and economic impact

Regulatory issues – compliance, hurdles and permitting gaps

General topics Technology strategy – internal and external considerations in creating a produced water

(All operational elements) management (PWM) strategy and action plan

Regulatory entities – global and regional players and controlling agency/agencies

Joint industry projects (JIPs) – multinational organisations open to additional

industry participation

Economics of water management – selected examples of cost benefit of PWM actions

Key technical resources – selected milestone resource documents.

Con c l u d i n g R ema r k s

Since no universal solution for PWM exists,additional experience and technology informationexchanges for PWM are needed to establish bestpractices and industry guidelines. In addition,regional environmental and economic assessmentstudies should be conducted on assets of the holdingbusiness. The outcome of such assessments should bethe basis for planning and designing new installations,improving existing facilities and choosing applicablebest practices. In order to successfully minimisenegative environ-mental effects of PW, integratedPWM should optimise the use of existingtechnologies, take into consideration local conditions,operational safety and engineering limitations andinclude the following prioritised list of strategies:

• eliminate discharges of PW to the marineenvironment;

• reuse water where possible (irrigation or pressuremaintenance);

• minimise water production by subsurface disposalin non-usable zones; and

• treat remaining production water.

Other essential elements to PWM include thecontinuous training of personnel and a completeunderstanding of the production process (fromreservoir characteristics to final discharge).

Current experience provides two main options forPWM, with re-injection and treatment with re-injection being the most promising solutions.Applied in many areas, re-injection is considered tobe the best option for protection of theenvironment, especially in shallow waters or nearecological sensitive sites.

Industry should continue to advance technologiesand improve safety of treatment chemicals. Furtherimprovements of environmental and economicperformance in E&P activities require continuousupdates and analysis of collected data. ■


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