This manuscript is an extension and update of oil field chemicals, which appeared in 2003. The text focuses mainly on the organic chemistry of oil field chemicals. As indicated by the title, engineers with less background in organic chemistry are likely to use this text, so various sketches of the chemicals and additional explanations and comments are included in the text with which an educated organic chemist will certainly be familiar. The material presented here is a compilation from the literature, including patents, arranged in the order needed by a typical job. It starts with drilling fluids and related classes of compounds, such as fluid loss, bit lubricants, etc. Then it crosses over to the next major topics: cementing, fracturing, enhanced recovery, and it ends with ninelines and snill.