Precommissioning to Startup: Getting Chemical Injection Right
Authors: Willmon Jeffrey G. , Edwards Mark A. 
Published: December 2007

This paper details lessons learned from practical field experiences concerning the design, construction, and commissioning of a production-chemical program for a green (new) field development. A competent program requires the interaction of various specialty-products and -services suppliers, including experts in flow assurance, modeling, fluid analysis, and specialty chemicals. All are engaged in the early stages of the project and retained as resources throughout.

Areas addressed for the design and implementation of a chemical-injection system (CIS) include the following:Exploration. Collected bottomhole samples are used for fluid characterization and risk assessment of any flow-assurance issues. From these initial data, prevention and mitigation strategies, including but not limited to chemical inhibition, are developed. Chemical products can be developed and/or screened for effectiveness and applicability from this initial assessment. This includes performance screening, chemical/chemical-compatibility testing, chemical/material-compatibility testing, and product stability (which is particularly important for umbilical applications).Facility design. Specifications for the processing system and equipment are detailed, materials of construction are screened for chemical and fluid compatibility, volume and deliverability requirements are determined, and the CISs are designed.Facility construction. Monitoring and oversight throughout the construction process are performed to maintain the integrity of the initial design.Operational strategies. Strategies will be developed that address initial flowback, startup, steady-state, and shut-in techniques.Logistic strategies. Strategies will be developed that address logistical concerns (e.g., product transfers and handovers).(Pre) Startup commissioning and testing of equipment. Cleanliness and operability of the system are an absolute must. The chemical day tanks and injection lines are flushed to specification.

Chemical-injection issues can be safely and successfully managed in new (deepwater) projects by proper fluid characterization and risk assessment; a field-development strategy that includes design, specialty treating chemicals, and operating plans; the involvement of specialists and specialty providers; and training and communication.

Introduction

As a result of location and/or depletion, petroleum resources have become harder to obtain. This difficulty has created a demand for newer and more sophisticated techniques for the recovery of oil and gas. As a function of this demand, chemical injection has become an important part in the proper performance of newly designed production systems, particularly in the deepwater area of the Gulf of Mexico.

Production chemicals play an important role in the enhancement of oil and gas production—they control corrosion, prevent organic and inorganic deposits (e.g., paraffin/wax, asphaltenes, and mineral scales), enhance flow characteristics, and aid in phase separation. These chemicals can be applied through a variety of techniques, including topside chemical-injection equipment and capillary/downhole injection. Regardless of type, any CIS must be designed to be effective, reliable, forgiving, and redundant.

Chemical injection used in conjunction with system design can maximize the production capacity of the system. For new, or green, fields that are in the design phase, the incorporation of chemical injection is valued because of the resultant tradeoff of capital expenditures (CAPEX) for operating expenditures (OPEX). The idea of trading CAPEX for OPEX is illustrated in Fig. 1. During project design and construction, maximum value can be achieved in minimizing CAPEX by use of proper chemical-injection techniques and procedures. Minimizing CAPEX is achieved by properly anticipating flow-assurance problems through risk assessment during design and by incorporating appropriate mitigation techniques into the construction of the facility.

At facility startup, maximum value is achieved through efficient commissioning and troubleshooting. Proper planning for the remediation of any difficulties will ensure success. Training and communication will be essential to the success of any project.

This paper discusses issues related to the incorporation of chemical injection into the design of a new project. In addition to design issues, suggested actions will be presented that will ease the commissioning and startup of the CIS. Throughout, lessons learned from practical experience will be presented where appropriate. It is the authors' hope that the suggestions presented here will prevent the statement "on the next platform…" and aid in getting chemical injection right on this platform.