Girasol, one of the largest heavy oil fields in Colombia, is located in the Middle Magdalena Valley basin. The field is composed of a shallow sequence of sediments of fluvial origin in which sandstone channels contain heavy oil of 11- to 13°-API gravities. Similar fields in the country are developed using thermal recovery techniques via vertical or deviated wells. As horizontal wells have proved to offer advantages for enhanced oil recovery, from the first stages the Girasol field development plan included the execution of horizontal wells to apply cyclic steam injection techniques. Four different stacked sandstone reservoirs, located at 1,100-ft to 1,600-ft true vertical depth (TVD) below surface, are the main targets. The project included a series of parallel horizontal wells of 1,200-ft to 2,350-ft lateral extension, with a fixed lateral spacing and vertically placed to drain one reservoir per well. The targets were geological, 10- to 20-ft thickness to maximize production. Horizontal well placement in this scenario—shallow, thin, and friable formations— is, in general, difficult to achieve with the use of conventional geosteering techniques, as they generally fail to identify unexpected changes in the reservoir geometry, increasing the risk of poor results. This risk was minimized by using deep, directional electromagnetic measurements while drilling, enabling the reservoir geometry mapping in real time, several feet from the borehole. Results of the use of this technology—combined with continuous inclination measurement near the bit and an advanced geosteering process— include 96% average net pay, minimization of unproductive drilling, rig time savings, and sidetracks avoidance after 24 horizontal wells drilled to date. The strategy used for horizontally placing wells in the Girasol field can be used in similar fields worldwide.

The success of a horizontal drilling campaign depends on the implementation of appropriate technologies and procedures to manage uncertainties and risks that may affect the overall economy of the project. This is the case for most fields in the Orinoco oil belt—the largest reserve of heavy oil in the world—which is mainly developed via horizontal drilling. As with other fields in the area, Junin-6 presents special challenges for horizontal well placement. The friable shallow reservoirs include some of the shallowest currently developed in the Orinoco oil belt. The main target sands range in thickness from 30 ft in the Arenas Basales (Basal sands) to 250 ft in the Oligoceno (Oligocene) reservoir. The lateral sections vary from 3,000 to 4,000 ft. This, combined with a high geological complexity, lack of 3D seismic data, and a limited number of correlation wells, makes the horizontal well placement a real challenge in many cases. Advanced logging-while-drilling (LWD) technologies had to be implemented in the challenging cases, such as in the Basal sands reservoir. A proactive approach based on bed boundary mapping technologies, combined whenever possible with point-the-bit rotary steerable systems, is being used to improve horizontal well placement in this field. The main results include net pay increase and cost reduction compared to wells executed with conventional technologies. The risk of unproductive drilling has been considerably reduced, especially in the thinnest formations drilled in this field. The best results were achieved when LWD bed boundary mapping was combined with point-the-bit rotary steerable systems, since this type of technology enabled better well trajectory control, faster execution, longer horizontal sections, and safer completions. This paper presents the main challenges for horizontal well placement in the giant Junin-6 heavy oil field and how they are being addressed with the use of advanced geosteering technologies.

The success of a horizontal drilling campaign highly depends on the implementation of appropriate well placement procedures to manage the constraints, risks, and uncertainties that may have a negative impact on the overall economy of the project. The magnitude of the uncertainties associated with the horizontal well trajectory and the geology is usually higher than the magnitude of that particular target within the reservoir that would maximize the production. The risk and uncertainty factors can be handled with the use of particular well placement techniques during the planning and execution phases. In the planning phase, these techniques include proper geological modeling methods and flexible well planning to allow room for changes if unexpected events arise while drilling. During the well execution, procedures should include the use of appropriate technologies to understand in real time the rock properties, the reservoir geometry, and horizontal well position, and, based on this information, to steer the well within the desired geological target. Girasol field, located in the Middle Magdalena Valley basin in Colombia, is composed of a sequence of sandstone channels that contain heavy oil with gravity ranging from 11 to 13° API. The main targets are five stacked sandstone reservoirs, from 10 to 35 ft thick, located 1,100 to 1,500 ft true vertical depth below surface. The field development included cyclic steam injection applied in horizontal wells to improve the heavy oil mobility. To maximize oil production and improve the cumulative steam/oil ratio, the objective was to place horizontal wells of up to 2,500 ft lateral extension within 3 to10 ft distance from the bottom shale of each reservoir. The horizontal well placement under this type of scenario required the use of precise horizontal well placement techniques and drilling practices to avoid exits from the predefined geological targets. These techniques relied on the use of deep directional electromagnetic measurements that enabled real-time bed boundary mapping. This paper presents the main challenges and uncertainties faced for well placement in the Girasol field horizontal drilling campaign, the technical solutions implemented, and the lessons learned in more than 80 horizontal wells drilled.

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.

Girasol, one of the largest heavy oil fields in Colombia, is located in the Middle Magdalena Valley basin. The field is composed of a shallow sequence of sediments of fluvial origin in which sandstone channels contain heavy oil of 11-to 13°-API gravities.Similar fields in the country are developed using thermal recovery techniques via vertical or deviated wells. As horizontal wells have proved to offer advantages for enhanced oil recovery, from the first stages the Girasol field development plan included the execution of horizontal wells to apply cyclic steam injection techniques.Four different stacked sandstone reservoirs, located at 1,100-ft to 1,600-ft true vertical depth (TVD) below surface, are the main targets. The project included a series of parallel horizontal wells of 1,200-ft to 2,350-ft lateral extension, with a fixed lateral spacing and vertically placed to drain one reservoir per well. The targets were geological, 10-to 20-ft thickness to maximize production.Horizontal well placement in this scenario-shallow, thin, and friable formations-is, in general, difficult to achieve with the use of conventional geosteering techniques, as they generally fail to identify unexpected changes in the reservoir geometry, increasing the risk of poor results. This risk was minimized by using deep, directional electromagnetic measurements while drilling, enabling the reservoir geometry mapping in real time, several feet from the borehole.Results of the use of this technology-combined with continuous inclination measurement near the bit and an advanced geosteering process-include 96% average net pay, minimization of unproductive drilling, rig time savings, and sidetracks avoidance after 24 horizontal wells drilled to date. The strategy used for horizontally placing wells in the Girasol field can be used in similar fields worldwide.