The fields of East Kalimantan, Indonesia contain several depleted gas zones of medium permeability (0.1 to 300 mD). Though the permeability is quite good for gas bearing formations, the majority of the wells targeting these sands have failed to produce at expected rates. In the 1980s, hydraulic fracturing was introduced to the area in an attempt to increase production. The treatments yielded limited success with many wells actually producing less after being fractured. This led operators in the area to believe that the formations could be water sensitive with damage from the injected fluids causing the poor results after fracturing. As laboratory testing has ruled out water-sensitive mineralogy, the suspected cause of damage has been attributed to a decrease in relative permeability to gas after the fracturing fluid has penetrated the pore throats (water block). The water block conclusion is supported by the low percentage of injected fluids that are returned after the treatment.In 2007, VICO performed four fracturing treatments using a conventional surfactant to aid in post-frac cleanup. Only 2 of the 4 wells that were fractured produced after the treatment. Again, a common problem between the wells was the poor return of treatment fluids during cleanout. The limited success of these treatments indicated the water block issue had not been resolved. After reviewing the results of the first four wells, three additional fracturing treatments were placed in similar reservoirs using a microemulsion additive instead of the surfactant. Though laboratory testing in cores between 1 and 8.5mD failed to show a significant difference between the microemulsion and surfactant, the wells fractured with the microemulsion additive consistently outperformed those fractured previously in terms of returned treatment fluids and incremental production. Paktinat et al. (2006) wrote that the use of fracturing fluids with microemulsion in unconventional tight gas reservoirs can help increase production by increasing the relative permeability to gas in the area surrounding the fracture. Our study shows that similar benefits can also be achieved in depleted gas reservoirs with permeabilities greater than 1 mD, even if the benefits can not be clearly demonstrated under laboratory conditions.
VICO Indonesia is the operator of the Sanga-Sanga Production Sharing Contract located onshore of the Mahakam delta, East Kalimantan, Indonesia since 1968. Over 40 years the PSC has produced 70% of the estimated original gas in place, supporting Bontang LNG plant. VICO has 7 producing fields, in a complex fluvial deltaic deposition with more than 2700 gas and oil reservoir, mixed of depletion and water drive mechanism reservoir. VICO production peaked at 1.5 BSCFD in 1995 then start to decline. Current production is in the range 385 MMSCFD of gas and 14500 BOPD of liquids from 400 active wells. In a situation of 46% annual base decline, to fulfill domestic and LNG contractual commitments and to optimize reserve recovery, VICO generated and implemented an integrated and aggressive work program called "Renewal Plan". This is an integrated approach between reservoir management and technology application; it provides a detail road map to onward development strategy. The main elements of the plan are extensive development drilling activities (conventional drilling, grid base drilling, cluster well drilling), low permeability reservoir optimization (horizontal well, hydraulic fracturing, radial drilling), production optimization (deliquification technique, permanent coil tubing gas lift for monobore type) and facilities optimization (reducing abandonment pressure by additional compression installation, wellhead compressor, debottlenecking). Technology application in drilling, completions, production and facilities optimization combine with synergy from multidisciplinary team have resulted in maintaining VICO production decline in the range of 5% (vs 46% base decline), allowing promoting and partially replacing the reserves at an attractive development cost, even after 40 years production life. This paper will describe the successful implementation of renewal plan in VICO Indonesia, which proved to be an efficient example of better reservoir management for optimum development of mature assets.
Several development strategies are currently being evaluated and applied by VICO, in order to increase the near term production rate and maximize recovery from the existing fields, within the Sanga-Sanga PSC, East-Kalimantan, Indonesia. This paper will focus on the "Cluster" drilling concept; that has been successfully applied within the Nilam field, which is the second largest field within the PSC. A combination of a complex fluvial-deltaic depositional environment, along with increasing development costs and reservoir uncertainty due to advancing field maturity, has driven the VICO development Team to re-evaluate the drilling and completion techniques being utilised in order to access the remaining hydrocarbon resources within the field. This re-consideration has allowed a number of novel and alternative solutions to the problems to be proposed, one of these solutions has been the "Cluster" well approach. The principal objectives of the "Cluster" approach are, to reduce the unit gas development costs, increase the short-term production rate and maximize the cumulative recoverable gas volumes from the field. Well cost reductions are being achieved through improved rig utilization and by the drilling of multiple wells from a single pad location. A dramatic increase in the short-term rates is being achieved through drilling dedicated wells to produce the shallow, higher permeability reservoirs. Finally, the recoverable reserves from the deeper, lower permeability reservoirs, which typically produce at lower rates but have a longer effective production life; are also being maximized through the application of dedicated completions (via the Dual Monobore concept). This paper will discuss the "Cluster" concept in detail, in brief a "Cluster" consists of the drilling of a "Mother" well which is then used as a reference well to acquire a full suite of open-hole data, this data is then processed in order to assess and define the opportunities within the immediate ‘local’ area of interest. The "Mother" well is then followed by the drilling 1, 2 or more "Daughter" wells from the same pad; the exact number of these "Daughter" wells being determined by the quality, quantity and type of information that is made available from the "Mother" well logs and tests. These additional wells were initially being drilled on twenty-foot centres, and the "Daughter" wells are typically constructed with some form of slim-hole approach, with minimal associated data acquisition in order to reduce the overall costs. This paper will present the results from the two sets of complete "Cluster" wells competed to date, within the Nilam field; and will provide a brief description of a third "Cluster" group that is currently being finished. The application of this technique has resulted in an average reduction in the well costs of more than 20% and a much improved set of well economics in both the short- and long- term; compared to drilling a single conventional well from a pad. The paper will also discuss the current candidate selection process, "Cluster" well design and header configuration, the drilling operations themselves and the subsequent post well evaluation.
VICO Indonesia is the operator of the Sanga-Sanga Production Sharing Contract located onshore of the Mahakam delta, East Kalimantan, Indonesia. The PSC has produced over 70% of the OGIP (original gas in place). The fields are relatively mature with the remaining gas resources locked up in either pressure depleted reservoirs or in low permeability reservoirs where conventional techniques have not been very effective in depleting these resources. During 2006, VICO decided to perform a pilot development of the larger/tighter reservoir tanks, utilising the horizontal completion technique as the preferred completion approach.To date VICO has successfully drilled and completed 5 horizontal wells, one in the Semberah field (S77H) and four in the Nilam field (N228H, N230H, N238H & N240H). The Semberah S77H well was drilled and completed in 2006 at a relatively shallow depth (~ 8000 ft.TVD.SS), in order to demonstrate the applicability of horizontal drilling technology within VICO. The four subsequent wells were drilled in the Nilam field, to depths of ca. 12,500 ft.TVD.SS. The N228H & N238H wells were drilled to test the productivity of horizontal wells at higher reservoir pressures; where condensate banking was thought to be a contributory factor to the dramatic transient and low deliverability seen from conventional vertical wells. Whereas the N230H and N240H wells, were drilled to test the productivity of horizontal completions in the depleted tanks where condensate banking may not be such a significant factor. All five of the wells are currently producing at relatively stable rates with significantly less decline, when compared to conventional offset wells. The initial gas production rates, that were achieved, were significantly higher than conventional wells producing from the same reservoirs and the total reserves recoverable per well are estimated to be 2 -3 times higher than a conventional well.The paper will describe in detail the candidate selection criteria, well design, well placement, drilling risks, tool reliability and the challenges steering a horizontal well in a geologically complex environment with high degree of reservoir uncertainty.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.