A Method for Optimizing Jet-Mill-Bit Hydraulics in Horizontal Drilling

Abstract

Summary Efficient cuttings transport is a major challenge in horizontal drilling; one can use a new type of jet-mill bit to overcome the challenge fundamentally. However, currently, there is no available method for optimizing jet-mill-bit hydraulics, which restricts the jet-mill bit from being widely used. In this paper, on the basis of the high-pressure water-jet comminution and jet-pump theory, a basic performance model of the jet-mill bit is developed. Then, the optimal parameter model for the jet-mill bit is presented according to the multivariable limitation theory; meanwhile, a method for optimizing jet-mill-bit hydraulics is also developed. With the method, one can determine the optimal jet-mill-bit hydraulics. Theoretical analysis and discussion show that the impact angle and the friction-loss coefficient are the key factors affecting the efficiency of the jet-mill bit; the impact angle is suggested to be set at approximately 70 ° and the optimal flow-rate ratio at appoximately 1.0; and the effect of rate of penetration (ROP, m/h) is not obvious, and one can ignore it. The optimal area ratio is almost not related to friction-loss coefficient and ROP, but it is related to the impact angle significantly. It provides drilling engineers a practical tool for determining the optimal jet-mill-bit hydraulics in horizontal drilling and promotes the jet-mill bit to be widely used.

Numerical and experimental investigation on the depressurization capacity of a new type of depressure-dominated jet mill bit

“…This triggered an idea of comminuting the cuttings right after they are generated, thereby cuttings accumulation in horizontal drilling may be eliminated (Chen et al 2016b). Chen et al (2016a, b, and c) developed a type of jet mill bit (JMB); this tool proffers a promising solution to the cuttings accumulation problem in horizontal drilling by comminuting cuttings into dustlike scale right after the cuttings are generated in the bottom hole. As it is, the JMB provides a promising solution to catch two birds with one stone: not only enhancing cuttings transport efficiency but also improving ROP by depressuring at the bottom hole.…”

“…As Chen et al (2016a) reported, the JMB is developed based on the jet comminution technique, in which particles can be broken into smaller ones instantly by high-speed impacts of these particles against a target. When comminution chamber and target are removed from the jet mill of the JMB, it is a jet pump.…”

“…Asymmetric jet stirs the bottom hole cuttings into a highly turbulent flow. The highly turbulent cuttings flow through the cuttings-suction channel into the mixing chamber under the lift of bottom hole flow and the suction of backward jet nozzles (Chen et al 2016a). The depressure-dominated JMB has small junk slots or flowby that conventional bits have around the bit to allow cuttings and drilling fluid to flow through the annulus between the bit and wellbore (Fig.…”

Drilling Performance Optimization Based on Mechanical Specific Energy Technologies

“…Maximizing ROP to reduce drilling cost in oil and gas development is the permanent objective of drilling researchers [1][2][3][4]. Numerous methods have been developed for optimizing drilling parameters to maximize ROP, and they are similar to drill rate and drill-off tests in that they observe trends in performance and attempt to identify the founder point, which is the point at which the ROP is maximized [5].…”

The Maximum-Allowable Well Depth While Drilling of Extended-Reach Wells Targeting to Offshore Depleted Reservoirs

“…Wells are considered as extended-reach wells (ERWs) when their horizontal displacement (HD) to true vertical depth (TVD) ratio are higher than 2.0 [1,2]. In recent years, the extended-reach wells envelope is continuously expanded (see Figure 1), and now it is not surprising to drill extended-reach wells with HD to TVD ratio greater than 6.0 or with HD longer than 30,000 ft [3][4][5][6][7]. Recently, the world's longest well at the Sea of Okhotsk was successfully drilled.…”