Under challenging market conditions, optimization and cost reduction become a priority, this paper presents the results and the best practices learned after the implementation of an innovative drilling fluid and cuttings separator in Latin America with three operators. This new technology has been field proven worldwide, in Latin America, operators in Argentina, Colombia, Ecuador and Bolivia have experienced improvements in overall solids control equipment efficiency and optimization of drilling operations. The use of new technologies regarding solids control equipment has allowed operators to significantly reduce drilling fluid consumption, waste volumes and improve the HSE profile in their operations. Three case studies are presented, each one of them correspond to the implementation of the new technology with a different operator in the region.

An operator is drilling exploration wells near Xanab field in Mexico's Southwest Marine region. The 8½-in. hole section is difficult to drill, with damaging shocks and vibrations occurring in the hard/ interbedded Cretaceous carbonates. These formations, with relatively high unconfined compressive strength (UCS) of 15,000 to 28,000 psi combined with alternating lithologies with chert nodules, have been drilled mostly with roller cone IADC-527X bits. Although the roller cone produced vibration-free operations, suboptimal rates of penetration (ROP) and short run lengths resulted in multiple trips to total depth (TD) of the section. Attempts were made to design polycrystalline diamond compact bits (PDCs) that could endure the difficult downhole environment by increasing diamond volume per blade. However, when encountering the hard formations, high vibration levels were still causing broken cutters in the nose/shoulder areas.In a new exploration well, a new fixed cutter bit was used. The bit is equipped with stinger conical diamond elements (CDE) with an ultrathick diamond layer that improves impact resistance, along with PDC cutters. A modeling system based on finite-element analysis (FEA) was used to design a new-type eight-bladed hybrid bit by positioning CDEs and PDCs from bit center to gauge on all eight blades. The unique cutter pattern would fail the rock with a combination of plowing and shearing action. To ensure all CDEs engage the formation at the beginning of the run, the elements were positioned at a height equal to the top edge of the conventional PDC cutters. This strengthens the bit by leveraging the superior impact strength of the CDEs. To deliver sufficient torque and to keep a vertical trajectory, a rotary steerable system (RSS) was selected, with an integrated positive displacement motor (PDM) to supply additional power.The bottomhole assembly (BHA) was run on the Keluk-1 well and drilled to TD in two runs, 30% faster (2.59 m/hr) than the average ROP of the nine 8½-in bit runs (seven with PDC and two with roller cone bits) in Xanab field (2.0 m/hr). The first bit run made 206 m and could have finished the entire section but was pulled for downhole tool failure. The second bit drilled 65 m to TD. This compares favorably to the nine-well offset average of 176 m. The RSS/motor combination worked as planned, providing the CDE bit with the necessary energy to maximize ROP while reducing stick/slip occurrence to less than 20% during the run. The reduced vibrations enabled the operator to maintain RPM (150 to 170) and weight on bit (WOB) (10 to 16 ton) when drilling the critical middle/lower Cretaceous mudstone with chert nodules. Previous runs in this section required reduced parameters to mitigate vibration, thus slowing ROP.Both bits were pulled out in excellent dull condition (0-1/0-0) verifying that the CDEs provided the added durability needed to drill through the challenging application. The increase in drilling performance saved 90 hours of rig time equaling USD 320,000. Field testing of other CD...

The Comalcalco Fault is a regional discontinuity that can present highly unstable zones when crossing it or its influence zone. This instability can lead to notorious increase in drag forces, cavings, stuck pipe events and ultimately loss of sections or the well. In the 12 ¼" hole of this exploratory well, this fault was present and despite some of the wells in the field managed to cross it without consequences, the influence was more notorious, and the problems lead to catastrophic results. While drilling the 12 ¼" section, the team was able to drill up to 4368 m without any relevant problems. The fault was intersected and drilled pass to section TD with the previous casing shoe at 2966 m. However, when a trip to surface was necessary, abnormal drag forces that avoided further movement of the string were experienced. This event led to the loss of the section and the need to perform a sidetrack, right across the influence zone of the fault at 3200 m. The risk was reassessed, and numerous preventive and mitigation measures were put in place, including drilling the section with a 12 ¼" pilot bit, enlarging the pilot hole to 13 ½" to cover the influence zone and having a contingency plan to run the 11 ¾" liner. Additionally, the formations were reinforced through drilling fluids design, and drilling and tripping strategies were optimized to minimize zonal invasion and influence zone disturbances that could lead to additional cavings. After the successful sidetrack, the section was drilled to 3600 m, 200 m below the fault’s influence zone. Good ROPs and low levels of stick and slip were observed despite several reaming runs while drilling. The contingency liner was run to TD, achieving the objective of isolating the influence zone of the Comalcalco Fault. With the problematic zone placed behind pipes, drilling the remaining of the original 12 ¼" sections with a 10 5/8" × 12 ¼" reamer resulted in the longest and fastest enlarged section to be realized in the field. With all the preventive measures put in place, the original 9 5/8" casing was set at its planned depth, avoiding an additional casing string and a change of the design of the completion.

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