First Application of Fiber Based LCM in Srednebotuobinskoe Oilfield, Russia

Abstract

Lost circulation is one of the main causes of nonproductive time during drilling in Eastern Siberia. In Srednebotuobinskoe oilfield major challenges are related to severely fractured igneous rock intrusion. Drilling through this interval is associated with constant severe to total losses. As a result, drilling velocity may drop below one meter per hour. Significant reduction of drilling time was achieved with application of an innovative fiber based LCM. Current paper describes results of this project. Curing losses in severely fractured igneous rock formations is challenging. In most cases the fracture width is not known; it can only be predicted. However, this prediction is not always accurate. An engineered fiber-based kill fluid was used to mitigate this lack of knowledge. Laboratory tests demonstrated ability to plug 1-5 mm fractures. System was applied in two wells in Srednebotuobinskoe oilfield. Fiber based pill was used in a combination with conventional LCMs. Additional operation time reduction was achieved by BHA compatibility. Average velocity of drilling through igneous rock interval was further compared to offset well from the same pad. Drilling through 140 meters igneous rock interval of the well took around 147 hours. Conventional LCM are sensitive to fracture width. Due to geological complexity of the interval they had limited efficiency. A novel LCM based on soft, short fibers allowed to overcome this problem. It has a dual plugging mechanism. It can bridge across fractures up to 5 mm and form a filtercake on the formation surface, mitigating losses to the fractures network. Applying this innovative solution in the 225 meters igneous rock interval of the second well (same pad) allowed to reduce drilling time to 119 hours. Thus, drilling became two times faster. Fiber based pill is also compatible with BHA, including telemetry. So additional time was saved on POOH/RIH operations. For the third well on the same pad pill placement strategy was further optimized. So, 135 meters igneous rock interval was completed in 23.5 hours. Drilling became 6 times faster comparing to the first well. Fiber based LCM showed high efficiency for mitigating severe losses in igneous rock intervals of Srednebotuobinskoe oilfield. BHA compatibility allowed to avoid additional POOH/RIH operations, providing extra value. Application of fiber based LCM led to significant acceleration of drilling igneous rock intervals. The pill was prepared on the well site with equipment available. Compatibility with surface and downhole equipment was also confirmed. Various successful field applications of fiber-based pills have been reported from various parts of the world. Current work presents first application of an engineered fiber based pill in Srednebotuobinskoe oilfield, Russia. The pill was pumped successfully in 2 wells in igneous rock intervals. Pill was placed through BHA. This solution allowed operator to achieve 6 times reduction of time required to complete the interval.