Continuous Pumping,Multistage,Hydraulic Fracturing in Kitina Field,Offshore Congo,West Africa

摘要

Many West Africa offshore fields are maturing and operators are completing secondary targets in their wells to maintain the economic operation of their valuable assets.Large quantities of reserves can be found in low permeability,consolidated,formations and new techniques are being investigated to improve the economic return of completing these formations.The Kitina Field,offshore from Pointe Noire,Congo,is one such field.Deeper sands have been produced to economic depletion and the operator is looking for alternative production intervals.The targeted reservoir is the 3A Sand at approximately 2200 meters TVD.The reservoir is a very heterogeneous lithology with varying quantities of siltstone,sandstone and calcite.The intervals of better porosity show a decrease in clay content,but the good "sands" can be either dominated by quartz or calcite with substantial variations with each meter of height.Three candidate wells were selected for placing multiple propped fractures using a technique that has been used for six years in North America.This technique utilizes a series of mechanical packers and frac ports that are sequentially shifted "on the fly" allowing continuous placement of more than one hydraulic propped fracture without shutting down the pumping equipment.During April to June of 2007,eight hydraulic propped fractures were placed in three re-completed,cased-hole wells in the Kitina Field with very encouraging production increases.During the first 90 days of post fracturing production,a production increase of 200% was achieved.This paper will discuss the steps that were taken to place these propped fractures from an ocean going tender barge using skid equipment and recommendations for the future applications of this stimulation technique.