Horizontal Well Acid/Propped Fracturing and Production Optimization via Multiple Hydraulic Jetted Laterals

Abstract Successful Transverse fracturing from horizontal wells can suffer several undesirable behaviours. During the pumping phase, point-source growth behaviour and stress-state driven geometry can be problematic, and then under production, radial convergence and pressure/conductivity deterioration with distance from the wellbore. While Longitudinal fracturing corrects these issues, it suffers from a complete failure to project the drawdown laterally away from the wellbore. However, today the ideal scenario can be readily achieved through the use of optimum Longitudinal fracturing of Transverse jetted lateral-pairs from conventionally drilled horizontal wells. Transverse fracturing is the dominant horizontal well stimulation geometry; but suffers a number of well documented shortcomings whereas the advantages of Longitudinal fracturing are themselves offset by poor drainage. A new technique of mechanically jetting opposing pair(s) of laterals, 600 ft tip to tip; followed by hydraulic fracturing combines the best of both of these geometries. This technique, when applied to a conventional horizontal well drilled in the minimum stress direction, offers multiple advantages. These advantages are related to improved hydraulic fracturing properties (reduced pressures, direct geometry control and enhanced fracture conductivity); as well as direct production enhancement, (complete linear inflow behaviour, projection of drawdown and improved drainage, EUR and RF over similar flow periods) when compared to conventional Transverse fracture placement. Lateral jetting, in vertical wells, is well understood; and has been a standard intervention practice over many decades. Thus, the placement of opposing laterals within a horizontal is merely an extension through a mechanical hurdle. Industry experience has demonstrated that such laterals can repeatedly penetrate as much as 100 m from the wellbore. Subsequent acid/propped fracturing of lateral-pairs results in numerous advantages. Emanating from a line-source, instead of a point-source, elliptical fracture growth results in surgical in-zone placement, with less dependence on the stress state. Initiation pressure and transient net-pressures are reduced due to the flow geometry. For both gel and acid, the ability to rapidly transport fresh/raw fluid to the lateral tip completely changes effective conductivities and acid-effectiveness, resulting in increased and enhanced width and conductivity. However, it is under production that the dramatically impacted aspects can be appreciated via this fracture placement approach. The drawdown itself is projected, by the presence of extreme or infinite conductivity tunnels, much closer to the tip of the fractures, thus resulting in an increased effective drainage radius of the overall system. Inflow to the fracture from the reservoir is initially linear, then Linear again from the frac to the lateral itself and then finally linear to the wellbore also. Pressure drop through the conductive fracture is minimised due to the distribution of flow. The result is improved Productivity Index, drainage and EUR. Multiplication of this effect, using optimised pairs of laterals along a conventional horizontal well delivers considerably improved economics, with reduced fracture and well count as a byproduct. This new technique (referenced herein as the "CTS" system/approach/method)for stimulating tight reservoirs allows for enhanced recovery, reduced well / frac count, optimised capitalisation and improved economics. This technique offers a revolutionary option, as well as a means of developing reserves that are currently stranded due to their: poor fraccability, challenging reservoir geometry, non-uniform drainage or undesirable contacts. Similar to the combination of fracturing with horizontal wells, this enhanced projection of the drawdown into formations along with fracture geometry control will create many new development opportunities particularly in conventional but tight-reservoirs.