Novel Slim-Matrix PDC Construction Boosts Drilling Efficiency: A Field Study of Deep Applications

Abstract

The ability to construct slim body matrix bits has been proven and demonstrated to be of value when compared to conventional matrix construction and steel body PDC bits. The new matrix material with enhanced toughness has shown it can take the drilling and dynamic loads of medium depth applications with low to medium compressive strength. However the technical limits possible using slim body construction needs to be established. Recent developments in applications drilling deep sections in medium to hard formations with extended intervals has shown a need to have heavy set PDC bits to be more hydraulically efficient. The construction of heavy set matrix bit has always suffered from tight junk slot area and open face volume because of the high blade count and dense cutting structure. The challenge with the rock column of deep sections is interbedding between soft formations and hard formations creating a need for a cutting structure to be durable but in the same time not suffer from poor cleaning when formation transitions to a softer member column. The new matrix material with enhanced toughness allows for the design of a slim-body PDC matrix construction. The technology was initially rolled out for 8½ in and 12¼ in shallow hole sections and results are recorded in SPE-KSA-113. The scope of this study is testing the structural integrity of this construction together with its effectiveness by extending the concept to heavy set bits and deploying them in deep interbedded rock column applications. The main value sought is that the drilling complexity and costs increase in deep applications and targeting improvement in ROP would have a direct consequence on cost per foot. In this context even an increase of 5% in ROP can have a significant effect if the hole depth is at 15,000 ft TVD. Thus this study focuses on measuring the success rate fo slim body matrix by measuring rate of ROP improvement while ensuring the structural integrity of this technology is not a risk at such depths. The severity of the applications in which these tests were conducted were evaluated when possible with rock compressive strength analysis and measuring that against ROP. The results portion of this part of the campaign (deep applications) has shown surprising results with more success rate percentage of improving ROP vs what was recorded in shallow applications (see SPE-KSA-113). The cost per foot effect was even more significant at such depth with the incremental improvement in ROP as the slim-body matrix construction responded to the variation of formation compressive strength. The slim body matrix feature proved its advantage in interbedded applications, where formations fluctuate from hard to soft and vice versa with no compromise to structural integrity even at the deepest applications drilled in Egypt's rock column.