Hydraulic Fracturing Optimizes Extraction of Reservoir Initially Considered Secondary

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 213110, “Hydrocarbon Production Enhancement on the Apaika-Nenke Field by Applying Hydraulic Fracturing as a Tool To Optimize the Extraction of Reservoir M2 Considered Initially as a Secondary Target,” by Franck Salazar and Nestor D. Vasconez, Schlumberger, and Christopher J. Mayorga, SPE, Petroecuador, et al. The paper has not been peer reviewed. As a result of reservoir conditions in Ecuador’s Apaika-Nenke field, a hydraulic fracturing pilot project was executed with the aim of maximizing production. After an analysis of the laminated reservoirs, a technique was implemented that generates higher fracture conductivity to reduce the drawdown during production and improve the connection through the laminations. The successful implementation of channel fracturing led to this technique becoming the preferred completion method in the field for wells requiring stimulation. The Apaika-Nenke structure is in Orellana Province of the Amazonian region inside of Block 31. Initial production tests in Well Apaika-1X showed an oil rate of 1,201 BOPD from the M1 reservoir and 653 BOPD from the M2 reservoir. In the Nenke-1X well, the oil rate was 1,600 BOPD from M1 and 328 BOPD from M2. Because higher oil rates were obtained from M1, the development phase that began in 2013 targeted the M1 reservoir as its primary objective. However, Well Apaika-A14 produced 150 BOPD only from the M2 reservoir. The maximum production from the oil field was 22,107 BOPD from M1 and 262 BOPD from M2 in April 2016 but has declined to 2,692 BOPD from M1 and 657 BOPD from M2. M1 is the main producing reservoir in Apaika-Nenke, which produces using conventional techniques. M2, however, was treated as a secondary target with low and difficult production levels; production from Well Apaika-A14 required hydraulic fracturing to reach commercial levels. This well raised the possibility of hydraulic fracturing in the M2 reservoir, opening doors for targets previously considered secondary. M2 is a highly shale-laminated sandstone with a glauconitic sequence. Shale/sandstone intercalations are found within the pay zone, a key feature for hydraulic fracturing. Well Apaika-A14 in M2 produces 14.9 °API oil with salinity levels on the order of 2,000 ppm chloride, while Well Nenke-B1 produces 16.3 °API oil and salinity levels of 9,000-ppm chloride. Well Nenke-B2 produces 14.7 °API oil with salinity levels of 5,600-ppm chloride. This information indicates that the oil producing from M2 is heavy. The oil viscosity is 104 cp at 194°F. A pore/volume/temperature analysis shows that the oil in the M2 reservoir is undersaturated and produces above the reported bubblepoint of 320 psi. The original reservoir pressure was 2,760 psi before initiation of hydraulic fracturing.