This paper presents the planning and execution process for a key matrix stimulation pilot project performed in the heavy-oil Chichimene field in the central Colombian province of Meta. An understanding of multiple aspects of formation damage, candidate well selection, laboratory testing, treatment fluid selection, onsite quality assurance/quality control (QA/QC), diversion considerations, and placement techniques was fundamental to achieving a successful treatment design. Results are presented in terms of a percentage increase in production rates, percentage decrease in decline rates, and skin value reduction. Because of current oil and gas industry economics, it is crucial to evaluate the return on investment for any well intervention campaign and apply an assurance process to help quantify the desired improvement in production results. This approach is primarily based on a workflow that includes several key steps: understanding the nature of and characterizing formation damage, reviewing necessary laboratory testing, validating candidate well selection, determining economically viable placement and diversion techniques, and performing QA/QC on site and post-treatment. Production results from the first five pilot wells are presented along with a review of the production decline and continuous improvement actions. Understanding the induced damage that can be caused by drilling operations, heavy-oil properties, and the potential for emulsion and wettability alteration, in addition to the need to ensure total fluid-fluid compatibility combined with low interfacial tensions (IFTs), can be crucial to achieving results above initial estimates. Aligned with current critical well intervention economics, a rigless operation with coiled tubing (CT) through the Y-tool of an electrical submersible pump (ESP) was selected instead of a traditional intervention with a workover (WO) rig. Because of long treatment intervals and large permeability variations, stages of foamed brine were included in the treatment schedule as a diversion method. A tuned frequency and amplitude tool was used to enhance the placement and effectiveness of the treatment as part of a CT bottomhole assembly (BHA). QA/QC sampling was valuable for treatment monitoring and enhancement. This paper presents a valuable basis for future candidate well selection and stimulation treatment design. The workflow and its application are a good reference for analogue fields in Colombia and other areas.

Conformance technology is the application of processes to reservoirs and boreholes to reduce water production, enhance recovery efficiency, or satisfy a broad range of reservoir management and environmental objectives. An operator desired to isolate aquifer zones and reduce water production in a horizontal section. First discussed is problem identification in the oil producing well; following, the application of reservoir simulation to determine the amount of and the most appropriate treatment application is discussed. Depending on fluid density differences and wellbore deviation, conventional conformance treatments can tend to slump/rise along horizontal or highly deviated sections, compromising the placement accuracy and overall treatment success. The stress-dependent (thixotropic) rheological properties of the conformance technology service used in this project provides rapid viscosity increase during placement, allowing the treatment to remain in place until in-situ crosslinking occurs at a predicted time, helping to provide a competent seal across the targeted area. A reservoir simulator was used to optimize the design of a conformance treatment and to evaluate the efficiency of the conformance solution. During pumping of the conformance system for the isolation of the lower zone because of water problems, it was observed that the entrance of the two sealing systems to the formation increased the pumping pressure, showing the sealing effect. Additionally, the thixotropic characteristic of the conformance sealant could help keep the systems in place until they acquired the consistency to complete the isolation of the water zone. Water production after conformance treatment was reduced by almost 65%, aligned to the expected results from diagnostics. A successful conformance operation was completed in a horizontal section, overcoming the natural tendency of standard fluids to slump/rise along horizontal or highly deviated sections. The proper conformance diagnostics with a reservoir simulator was vital to the success of this project.

Two producer wells in the Chichimene field of Colombia were converted to injector wells as part of a water management and pressure control strategy. Because of zero injectivity in these wells, the operator desired to stimulate for a successful disposal-type reinjection to decrease the 70,000 bbl of water being discharged. This paper describes the planning and performance of stimulation operations in these two injector wells. A proper diagnostic helped to identify damage to be attributed to fines migration. Based on a consideration of petrophysical properties and corresponding logs, an acid system was designed and tested in the laboratory. Diversion options during stages of sequenced acid preflush, hydrofluoric acid, and postflush were reviewed. The desire to minimize the tubular exposure to acid in the wellbore and to place the open end of the tubing in front of the perforations made the option of coiled tubing appealing. With this option, the placement of the necessary sequential stages of the sandstone acid treatment would be possible across discrete intervals. Both wells experienced an injectivity index of zero before the acid treatment. The average daily injection of well CH-182 dramatically increased to 19,000 BWPD after the acid treatment. The average daily injection of well CH-183 dramatically increased to 20,000 BWPD after the acid treatment. These two wells currently have higher injection capacities than any other wells in the Chichimene field; combined, they inject 43,000 BWPD at maximum peak. The discharged water volume before the stimulation treatments was 70,000 bbl. After stimulation of the injector wells, the discharged volume is 30,000 bbl, representing an approximately 60% reduction in discharged volume.

Neste artigo apresentamos uma abordagem de teste de software baseada em modelos que foca na identificação, automatização e derivação completa, ou parcial, de casos de teste a partir da composição de modelos UML que descrevem alguns aspectos do sistema que está sendo testado. Nossaabordagem provê uma considerável redução de esforço na geração de testes, aumentando a eficiência dos testes, diminuindo o ciclo de teste, e evitando a confecção tediosa e propensa a erros de um conjunto de casos de testes. Por fim, apresentamos um estudo de caso para demonstrar de modo prático osbenefícios da abordagem proposta.

This paper addresses issues concerning treatment execution and discusses results from successful coiled tubing (CT) hydrajet assisted fracturing (HJAF) treatments performed during a campaign in a mature oil field located in northeastern Colombia. The Tibú field is a mature field in northeastern Colombia having low-permeability reservoirs that necessitate stimulation techniques, such as hydraulic fracturing, to increase production by increasing the contact area of the producing intervals. Additional challenges exist, including small well location pads, complex community relationships, and security problems that inhibit simple, fast, and efficient operations. To address these issues, a solution was proposed involving a blend of conventional proppant fracturing with the versatility and efficiency provided by a CT-deployed hydrajet perforated pinpoint stimulation method. These operations included well cleaning using slow-rotating wash tools and correlation for depth control using a gamma ray/casing collar locator. More than 40 wells have been completed using CT HJAF treatments in this field. Some technical advantages provided by the application of this technique are a higher perforating efficiency and a significant reduction in near-wellbore (NWB) friction, yielding reduced risk of premature screenouts, enabling higher pumping rates, and generating longer fractures. Post-fracturing oil production results met expectations for this mature oil field, proving the economic viability of this technique for successful multistage hydraulic fracturing in a short period of time. For most of the wells, all completion activities, including up to three fracturing stages, were performed in four days. This paper shows how the proposed CT application for HJAF operations can yield significant benefits and improve the level of sustainability in these types of mature oil fields.