The History of Hydrocarbon-Based Ultrafine Cement Slurry System for Water Shutoff in Offshore Mexico

Abstract

Excessive water production can detrimentally affect the profitability of hydrocarbon-producing wells if not controlled properly. Water cut present in the oil stream from wells producing in several offshore Mexico fields is an issue of critical importance because oil production is sent to exportation. Lack of water handling facilities forces operators to monitor wells with water cut as low as 2.0%. Water production is normally controlled by decreasing the choke size, but in the worst cases can require shutting the well in completely, causing a negative impact on the production of the fields. Two main drivers of excessive water production in these mature fields are the influx of water behind the casing and/or water flowing through the natural fractures of these carbonate reservoirs. This paper describes the successful field implementation of a selective hydrocarbon-based ultrafine cement (UFC) slurry system to slow down water production in offshore Mexico.The UFC slurry consists of ultrafine cement with an average particle size of 2.5 µm, a surfactant, and a hydrocarbon carrier fluid (i.e., diesel). Because the slurry is hydrocarbon-based, it remains inactive when contacting an oil-producing zone. When the system contacts a water producing zone, the slurry will remain pumpable for an additional 20 to 30 min before beginning to set. The delayed setting of the cement slurry is ideal for placing the UFC slurry into water-bearing formation fractures some distance away from the wellbore. The slurry is designed to selectively shut off water flowing into the wellbore and is applicable up to 204°C. This paper describes the field implementation of the UFC slurry system in offshore Mexico to seal off unwanted water flowing through natural fractures and/or behind the casing. A variety of case histories are discussed in detail along with postproduction numbers after the treatment. Numerous UFC treatments have been performed in southern Mexico. 2

Production Optimization of an Oil Well by Restraining Water Breakthrough

“…This results in the premature closure of these wells due to production that has become uneconomically profitable. Different techniques have been employed to control the problem of water ingress in oil wells, each type of problem has solution options that extend to mechanical, chemical, and completion solutions [21][22][23][24][25]. Multiple water control problems are common and a combination of these solutions is required.…”

“…Nonaqueous cement slurries have been used for many years to prevent unwanted water or gas production and to repair holes/cracks or other pathways that could have formed in the casing, cement column, or interface [21]. The authors of [22] have described the successful best practices and mistakes of the implementation of the ultra-fine cement slurry system in Offshore Mexico to seal off unwanted water flowing through natural fractures and/or behind the casing. The results of successful applications of polymer gels to control undesirable water production in mature fissured reservoirs in northern Italy have been presented in [23].…”