NACE 21415

Abstract

Introduction It has long been recognized that certain additives used in oil and gas production (“upstream”) field development and operations can impact downstream refining processes. Likewise, chemicals are sometimes added or cargo mixing can occur in transportation of crude oil from the producer to the refiner, also altering the processing properties. Production processes, such as deepwater production, bitumen mining, heavy oil production using steam, hydraulic fracturing of tight formations (“fracking”) are highly dependent on chemical additives during production. For hydraulic fracturing, chemical additives also play an integral role during well completion / stimulation and the large number of wells per unit of production cause the likelihood of drilling, completion, and stimulation additive carryover to increase. Refining of the various Canadian heavy oils and synthetic crudes derived from those sources has become common in Canadian, upper Midwest (pipelined), and Gulf Coast (railcar transport) US refineries. Also, output from the primary light tight oil (LTO) producing fields, Eagle Ford and Bakken, has increased more than tenfold since 2010 and US refiners have altered their strategies to include significant refining of LTO because of the pricing advantages of those crudes. Global development of such resources lags that in the US, but is also increasing rapidly. As an example, since 2010, ad hoc discussions indicate the organic chloride contamination is potentially increasing. Organic chloride contamination was found in pipeline crudes in western Canada and California. A South American refinery suffered multiple failures in their naphtha hydrotreater (NHT) in mid-2010 as a result of organic chloride contamination in their pipeline crude source. This refiner had processed nominally the same crude from this pipeline for many years without incident. Organic chlorides have also been detected in crudes supplied from West Africa and offshore Brazil. Taken together the above facts demonstrate an increasing likelihood of drilling, completion, maintenance (cleaning fluids) and/or production additives being present in the crude oil delivered to refineries. Many additives, even if present in the crude, are innocuous at the levels commonly used. Others can have a large impact on refining operations. These effects are not limited to the crude distillation unit (CDU), but can affect many downstream and conversion units as well. While there has been some systematic study of the effects of upstream and midstream additives on refining including the development of analytical methods; most of the knowledge has been derived from inference, experience, and nonstandard test methods. It is a purpose of this technical committee report to collect such knowledge and experience and to serve as an aid to refiners in evaluating the impact of new or changing crude diets relative to crude additives on their operations especially as it relates to asset integrity. The scope of feedstocks to be discussed in this report includes: conventional crude (or pool) oils, unconventional oils (such as bitumens, synthetic crudes derived there from, dilbits, synbits, etc), shale or tight oils, and natural gas condensates. More complete definitions and characterization of these feedstocks are included in the report.