High-Energy Perforation and Fracturing (HEPF)—Great Revolution of Perforation for 21st Century

Abstract

Abstract Based on the snalysis of 50-year-long experiences of conventionalperforation, this paper presents an innovative perforation techique that twodifferent types of high energy-shaped charge and propellant are being putinside the gun, and these two types of energy would be ignited at the same timebut be put in action separately, therefore perforation and fracturing could becombined perfectly, forming high conductine tunnel-fracturing network andgreatly increasing percolation area around near wellbore. Surface concretetarget test shows length of semi-radial fracture is 2500mm. More than 700 wellsapplication proved that this technique is safely operating, and greatlyincreasing production and injection. At present, the comprehensive system ofapparatus study and manufacture, surface test, operation art, modern downholetest and intelligent software is being composed, which will make progress andrevolutionize international perforation. Summary The final success of a well—productivity and lifetime—is dependent onconnection degree between wellbore and formation and this connection is carriedout by perforation. Over a long period of time on one hand, solid particles ofmud and killing fluid plug pores of near wellbore rock, forming a radius of1.5–2.5m damage area;on the other hand, since 1948 according to the guidingprinciple of "deep penetration and high shot density", penetration of shapedcharge perforation has been increased to 0.7m by means of adding explosive loadand increasing shaped charge size. But considering the further development andits current situation, there are still some problems unsolved, such as:Increasing shaped charge size and shot density would be restricted bywellbore space, perforator space, casing and cement sheath, etc.;Unitary perforation effect;Small penetration;Extrusion mechanism would result in compaction damage, and it is reportedthe permeability of compaction damage area will be reduced to 25% of originalone ;20–75% of shaped charge energy is being unutilized (i.e.be unutilized formaking perforation tunnels). Above all it is important to inherit the advantages of conventionalperforation and explore the new method. Based on conventional perforation and HEGF (High Energy Gas Fracturing), HEPF breaks through traditional ideas, it combining perforation and fracturingwhich are put in action sequentially, resulting in forming tunnel-fracture typefracture network around the near wellbore, therefore greatly increases nearwillbore percolation area, overcomes restriction of critical conditions, fullyutilizes residual energy of shaped charge and removes compaction damage createdby perforation. From the end of 1996 till 1999, more than 700 wells applicationin domestic fields shows average production has been enhanced by 100%. By nowHEPF series products and auxiliary arts have been completed. Fundamentals and Characteristics Fundamentals Inside the strengthened gun with relief holes, shaped charge and propellantare combined, while explosive fuse ignites shaped charges, the propellant wouldbe fired by residual energy and generate explosive combustion gas pressure. Transient time differential and pressure—time course of shaped charge explosionand propellant explosive combustion must be effectively controlled, thenrealize that shaped charges perforating in different phases and high-pressuregas fracturing following the perforation tunnels. These two-step action willform deep tunnel-fracture type penetration and greatly increase percolationaround near wellbore area. Fundamentals Inside the strengthened gun with relief holes, shaped charge and propellantare combined, while explosive fuse ignites shaped charges, the propellant wouldbe fired by residual energy and generate explosive combustion gas pressure. Transient time differential and pressure—time course of shaped charge explosionand propellant explosive combustion must be effectively controlled, thenrealize that shaped charges perforating in different phases and high-pressuregas fracturing following the perforation tunnels. These two-step action willform deep tunnel-fracture type penetration and greatly increase percolationaround near wellbore area.