Performance Step Change in Shallow Extended Reach Wells in Venezuela Enables Drilling Optimization and Increased Heavy Oil Production

Abstract

In an operation in the Venezuelan Faja, well placement and rotary steerable systems (RSS) enabled drilling faster, longer, and shallower ERD wells than those that have been drilled with mud motors in the field over last 20 years. The results demonstrate a performance step change in this area.Standard drilling in the Faja includes dogleg severity (DLS) requirements as high as 8°/100 ft and rates of penetration (ROPs) as fast as 2,000 ft/hr; these were perfect conditions for using mud motors to drill build sections and horizontal wells. As drilling in the Faja moved south, reservoirs at true vertical depth (TVD) from 1,200 to 1,600 ft started to be developed. Shallow reservoirs and even higher DLS made it inefficient to drill the long 4,000-ft extended reach sections planned as this requires multiple pipe swaps to redistribute heavy bottomhole assembly (BHA) components and wiper trips to clean the hole to allow weight-on-bit (WOB) transmission to reach the bit.To reduce tortuosity, torque and drag, and stuck-pipe events; to improve hole cleaning, WOB transmission, and ROP; and to drill longer horizontal sections, a point-the-bit RSS was tried for the first time in Junin division. The first RSS well drilled in a shallow horizontal well exceeded all objectives and expectations set. Seven more horizontal sections drilled with the same RSS proved the system was robust enough to break a different drilling record on each well.The current shallow extended reach well (SERW) record in the Faja was drilled with a mud motor to 1,231 ft TVD with 4,404 ft of horizontal section and a TVD versus horizontal stepout ratio of 1:4.4. Advanced drilling engineering, bed boundary mapping LWD technologies, RSS, and improved drilling practices in six horizontal sections enabled drilling to similar ERD ratios, while breaking records for ROP, horizontal section length, and drilling and completion speed at similar TVDs.The performance step change in the Faja accomplished through the use of RSS and novel drilling practices has enabled increasing heavy oil production through drilling longer horizontal sections and through the reduction of mud filtrate and formation damage. The performance increase along with lesser tortuosity and friction factors have allowed drilling longer horizontal sections, saving valuable rig time, producing wells earlier, and running liners to total depth (TD) trouble-free unless stopped by oil production.

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.…”