Implementation of a Robust Deepwater Sand Monitoring Strategy

Abstract Sand detection data has traditionally been used to protect asset integrity and prevent hydrocarbon release by limiting the potential for erosion of chokes, piping and valves. However, now in the Shell's Deepwater Gulf of Mexico oil and gas fields there is an additional need to ensure well integrity by appropriately characterizing the produced solids in order to monitor completion integrity and the effectiveness of bean-up rate and drawdown-constrained production operation schedules. The procedure developed within Shell allows us to critically evaluate how much and what type of solids are produced during choke changes and during sustained high-rate production, to differentiate between damaging solids and benign solids (small size or non-reservoir sand), and to monitor the wells for the onset of damage to sand-control integrity (sand control is generally required in Gulf of Mexico unconsolidated sands). Our detection system combines an acoustic sensor, a slip stream device to sample solids entrained in the flow stream, and a unique on-site microscopic analysis to identify the solids that have been collected. In addition to the off-site calibration and testing of acoustic sensors, we perform field calibrations by injecting into the flow line, upstream of the sensor, sand of sizes and compositions consistent with reservoir sand and fines and also proppant that is used in our gravel pack and frac-and-pack completions. Designed into our production operations is a schedule for pulling and filtering a fluid sample to capture solid particles. Sampling is also triggered by acoustic sensor readings exceeding preset alarm levels. After a sample is procured, it is examined microscopically by the operator and an image is captured for documentation purposes, to send to an off-site expert for identification, or transmitted in real time for remote expert interpretation. Examples of successful execution of this process will be presented, such as one high-rate gas well which set off the acoustic sensor alarms when restarting after an unplanned shut-in. The well was immediately choked back, while a sample was filtered and analyzed. The rapid identification of benign solids (inorganic salts which were a byproduct of the drill-in fluid) allowed the confidence to resume full rate production, thus preventing the loss of $150,000 cash flow per day.