Deepwater oil and gas fields are generally classified as developments located in water depths greater than 500 m.1 Applying production chemicals in deepwater fields presents multiple challenges because the operating temperature of deepwater oil fields is often greater compared to that of shallow or onshore developments. Furthermore, the extended reach of deepwater chemical umbilicals results in longer residence times for the chemicals within them and lengthy exposure to the high-pressure (HP), low-temperature environment. Long-term stability of chemicals under these conditions is an essential requirement in maintaining the integrity of the injection system and product efficacy. The HP in the umbilical can increase the viscosity of a product to such an extent that it cannot be injected. In extreme circumstances, production chemicals can become totally unstable in the umbilical, causing a blockage that results in costly remediation workovers.
To reduce the costs associated with constructing deepwater fields, the number of chemical umbilicals installed is often minimized, which necessitates the use of combination production chemicals. The most common multipurpose products used in deepwater fields are combined scale and corrosion inhibitors. This work details the approach taken to develop two deepwater multifunctional products that have functionality not generally found in a single product. The first product is a bifunctional corrosion inhibitor/demulsifier, and the second is a corrosion inhibitor blended with a non-triazine hydrogen sulfide (H2S) scavenger.
Hydrocarbon production currently occurs in a variety of onshore and offshore locations. Most offshore production in shallow water (< 500 m) has reached maturity, with most of the more accessible reserves having already been exploited. As a result, exploration and production in offshore environments has been extended to deeper water (> 500 m), which usually incurs more expense and overall project risk for operators and service providers. Production from deepwater oil fields is expected to grow by 40%, to 10 million bpd (10% of total global output), by 2025.2 Figure 1 shows the regions where deepwater oil production is expected to grow. Large development projects are already underway in deepwater Atlantic areas of the UK and Norway, the Gulf of Mexico, Campos pre-salt basin in Brazil, West Africa, and Australia.