Handil Field is a mature oil and gas field located in Mahakam Delta, East Kalimantan, Indonesia, developed since 1975. Handil reservoirs were deposited in a fluvio-deltaic environment. Oil reservoirs mainly located in shallow zone, whereas gas bearing reservoirs are mainly located in lower main until deep zone. Handil shallow zone consists of multi layer reservoirs located at depth 200 to 1500 m TVDSS. This zone is penetrated by different kinds of completion well techniques: gravel pack well for shallow zone and tubingless and dual string well for main and deep zone. The oil production from shallow zone is supported by gas lift system. The characteristic of shallow reservoir is poorly consolidated to unconsolidated sand with strong aquifer support. Due to sand prone reservoir, sand control technique is mandatory to prevent sand production when producing the oil. Gravel pack is commonly used as completion technique. Yet it still has limitation in number of reservoir coverage. As an alternative solution to produce remaining uncovered oil reservoirs, resin sand consolidation (SCON) is chosen. As the impact of bottom-up perforation strategy applied in Handil field, SCON implementation in ex-main and ex-deep zone wells are continuously emerging. Currently, several wells start producing from shallow reservoirs. Extensive preparation should be performed such as gas lift installation, tubing integrity, cementing, and site preparation in order to perform SCON in these types of wells. In terms of SCON target selection, several assesment should be performed to deal with SCON chemical limitations. SCON technique in Handil shallow oil reservoir was put on pilot project in 2011. Until End of 2018, 19 jobs have been implemented in different type of well architectures. In term of production gain, SCON jobs have been delivering ~1,100,000 bbls cumulative oil production with 100% success ratio on job execution and durability of the resin (no early sand breakthrough on surface). In 2018, 11 SCON jobs were performed with an average production gain 400 bopd and reserves 80,000 bbls. Due to its profitability, robustness, and applicability, SCON remain the main option to unlock oil potential of the remaining unperforated shallow reservoir in Handil Field.

Handil is a mature oil and gas field with dozens of wells drilled within 70-m distance. It has been developed since 1975 and operated by Indonesian national oil company, PT Pertamina Hulu Mahakam. Handil shallow reservoirs are located at depths between 200 and 1500 m true vertical depth (TVD). It has strong aquifer support and unconsolidated permeable sandstone reservoirs with poorly sorted grain size, requiring gravel pack completion. Since 2005, there have been 39 wells completed with gravel pack, contributing 40% of total Handil field production. Handil gravel pack wells are facing productivity impairment; several production tests indicated that 30% of the completed zones have a very low productivity index (less than 0.5 STB/D/psi) after a few years of production. Organic clay acid (OCA) was proposed as a matrix acidizing technology to dissolve the fines in the critical near-wellbore matrix. For many years, matrix acidizing has been used to remove formation damage or improve productivity in formations containing siliceous clay. The most commonly used treatment fluid is mud acid, which is a mixture of hydrofluoric acid (HF) and hydrochloric acid (HCl). In many conventional mud acid treatments, after an initially good response to the treatment, the production falls to levels similar to those before the treatment; this is thought to be due to the precipitation from the reaction of HF with silica material on feldspar/clay, which results in more hydrated silica gel. Unlike conventional mud acid, OCA can allow a deeper live-acid penetration into the formation and limit possible reaction-product precipitates, which will enhance the effectiveness of the stimulation treatments. Two OCA trial treatments were executed through coiled tubing. In the first job, the chemicals created an emulsion that was not compatible with fluid on the surface facilities. Demulsifier treatment on the surface successfully diluted the emulsion. Some adjustments on chemical composition have been applied on the second job, which successfully removed the emulsion. The pilot test yielded total oil production up to 900 BOPD (4,000 BLPD) instantaneous gain with ~80% improvement on productivity by reducing skin from >100 to 5. Currently, both wells are still flowing after 6 months of production. Following this success story, more than 11 OCA jobs are planned to improve the productivity of the existing zones in 2018. A recent matrix acidizing campaign in Handil shallow wells, highlighting the damage verification, candidate selection, acid chemistry, operational constraints, production results, and future opportunities. The logistics which include the flowback of spent acids and acid neutralization in the swamp area, and the addition of demulsifier in surface facilities will also be discussed. There were no core samples available to run a formation response test to the acid prior to the matrix acidizing treatment.

In common practice, gravel pack completion is beneficial as sand control in a typical unconsolidated sandstone reservoir. However, with poorly sorted sand grains, fines migrate and deposit at the gravel-pack matrix, causing permeability reduction and hence, decreasing well productivity. Matrix stimulation has been proven to remove the fines blocking the pore throat. The desired solution has been carefully selected to have prolonged well production. Organic clay acid is chosen for to its ability to have deeper penetration and to create a thin coating on the pore surface to prevent fines migration. Laboratory testing and field application were performed in parallel. A core flood test with reservoir core samples showed a result of 111% regained permeability. Ten treatments were conducted and showed good results. The productivity index increases 10 times on average. From those experiences, a benchmark was identified, which factor determines the success of a treatment. This paper presents the project preparation and execution, key reasons to success, and the way forward.

Managing oil and gas reserves and resources of Pertamina, an Indonesia state owned energy company, has always been challenging processes as the company's portfolio is sparsely located throughout Indonesia. Moreover, since November 2013 the company has also managed its international assets spread across three regions, namely Africa, Asia, and Middle East. In total, there are ~480 fields and ~870 geological structures with different degree of geological background, environment, uncertainty, and maturity of the fields/projects. Obviously, to cope with all those complexities, Reserves Management Department need to figure out its way to properly manage reserves and resources of the company. Reserves and resources of oil and gas is a key strategic priority of the company. It is aligned with both portfolio management and development and production of the assets. Company decision in terms of work program and budget is also mainly derived from reserves and resources potential of the projects. Therefore, to obtain a standardized reserves and resources management, the company has launched company guideline which is mainly influenced by SPE Petroleum Resources Management System (SPE-PRMS, 2007). SPE-PRMS is a project-based system, where reserves and resources estimation, categorization, and classification are on project basis. To properly manage all the projects, since 2019, Reserves Management Department introduced a tool named Project Box which enable reserves analyst to properly map all the projects, evaluate the portfolio, and monitor the progress of the project both in development and exploration phase. Furthermore, to be aligned with company's digitalization campaign, all the reserves and resources data, Project Box, and many other strategic information are stored and maintained in an in-house software named Promyst which will be launched in early 2021. This tool will enhance data accessibility for both management and analyst, increase data integrity and security, provide data analysis platform, moreover this software could also generate cost efficiency for the company. In 2017, along with the final version of the company guideline, the company has fully adapted PRMS. This paper will explain how the company adapt PRMS to its company guideline in which some necessary adjustments took place with respect to company's business processes, the application of Project Box throughout all company's subsidiaries, and implementation of Promyst along with its features and future projection of the software. The result and benefit of implementing those items will be explained in this paper. These extensive works performed by the Reserves Management Department contribute significantly to the company not only for technical but also for commercial aspects therefore promoting a good corporate strategic planning and decision making.