Analysis of the availability of water resources using the Thornthwaite-Matter water balance method with dual reservoir development in residential locations in Tangerang regency

Many settlements still use groundwater sources and this can cause a decrease in the ground water level. There is a need for alternative sources of water to meet the water needs of settlements. The purpose of this study was to determine the magnitude of the surplus or deficit of water in Tangerang Regency, Indonesia and also to determine the amount of water demand for the population in the region. Therefore, it is necessary to analyze the planning of dual reservoirs in providing groundwater for residential areas in overcoming the problem of drought in the dry season. This research method uses Thornthwaite-Matter water balance analysis and multiple reservoir design planning. The results showed that the estimated water surplus occurred from January to April with a magnitude between 25.07 mm to 186.09 mm. The water deficit occurs from July to October with a magnitude between 127 mm to 219 mm. The pattern of water consumption in the household is used as a reference for making reservoirs to maintain the availability of air in residential areas. The dual reservoir will be equipped with sensors that can help determine the water level so that it is easy to detect water needs and can prevent water wastage.

First Multilateral Well in the Most Congested Field in Abu Dhabi, Case of Study

This paper will highlight the first level 2 Multi-lateral well in BAB Field with permanent limited entry liner completion in the lower borehole to enhance accessibility and production. The well presents a technical milestone to the company in the development of multiple reservoir by combining two (2) wells from different reservoir and produce from both by using same surface well construction. At initial stage, the economics related to the implementation of the multilateral approach were analysed. Calculation was done by comparing the cost related to the technology application against the cost to prepare one (1) location plus completing a well up to the 7″ liner and mobilizing the rig twice. Then, it was necessary to select the candidate wells to be drilled from the same slot where synergy between Study team and drilling team was in place in order to ensure proper target alignment to make feasible the drilling and completion operations at the same time that the production targets were fulfilled. This project confirmed the feasibility of multilateral well application in a very congested field in terms of wells construction and surface facilities. In order to achieve such goal full synergy must be in place to select proper wells candidates and align targets. Cost reduction is massive considering the elimination of three (3) well phases plus avoidance of one (1) location construction and also the elimination of 1 rig move represents a big impact in terms of economics. Furthermore, the impact in terms of the risk reduction must be considered By combining two (2) wells in one (1) and eliminating three (3) phases in the standard well construction the harmful impact of location preparation, drilling fluids and cuttings on the environment is reduced by 45%, especially with oil base mud system. Geological problems can be observed during drilling each phase of a new well. However, drilling multilateral wells will reduce this occurrence. Well was completed with 7″× 4-1/2″ top packer, 4-1/2″ Slotted tubing and seven (7) swellable packers in lower borehole as well as Dual upper completion with 7″ single retrievable and 9-5/8″ dual retrievable packer and 2-7/8″ and 3-1/2″ tubing combination in both short and long string. This paper presents ADNOC Onshore first and successful experience in the deployment of new acquired technology for the Drilling multi-lateral / dual completion systems in BAB Field. The screening criteria for selecting the system as well as the benefits realized and lessons learned from this experience are also discussed together with the design simulations required to ensure the success of the well construction.

Multiple Strategies Based Salp Swarm Algorithm for Optimal Operation of Multiple Hydropower Reservoirs

Reasonable optimal operation policy for complex multiple reservoir systems is very important for the safe and efficient utilization of water resources. The operation policy of multiple hydropower reservoirs should be optimized to maximize total hydropower generation, while ensuring flood control safety by effective and efficient storage and release policy of multiple reservoirs. To achieve this goal, a new meta-heuristic algorithm, salp swarm algorithm (SSA), is used to optimize the joint operation of multiple hydropower reservoirs for the first time. SSA is a competitive bio-inspired optimizer, which has received substantial attention from researchers in a wide variety of applications in finance, engineering, and science because of its little controlling parameters and adaptive exploratory behavior. However, it still faces few drawbacks such as lack of exploitation and local optima stagnation, leading to a slow convergence rate. In order to tackle these problems, multiple strategies combining sine cosine operator, opposition-based learning mechanism, and elitism strategy are applied to the original SSA. The sine cosine operator is applied to balance the exploration and exploitation over the course of iteration; the opposition-based learning mechanism is used to enhance the diversity of the swarm; and the elitism strategy is adopted to find global optima. Then, the improved SSA (ISSA) is compared with six well-known meta-heuristic algorithms on 23 classical benchmark functions. The results obtained demonstrate that ISSA outperforms most of the well-known algorithms. Then, ISSA is applied to optimal operation of multiple hydropower reservoirs in the real world. A multiple reservoir system, namely Xiluodu Reservoir and Xiangjiaba Rservoir, in the upper Yangtze River of China are selected as a case study. The results obtained show that the ISSA is able to solve a real-world optimization problem with complex constraints. In addition, for the typical flood with a 100 return period in 1954, the maximum hydropower generation of multiple hydropower reservoirs is about 6671 GWh in the case of completing the flood control task, increasing by 1.18% and 1.77% than SSA and Particle Swarm Optimization (PSO), respectively. Thus, ISSA can be used as an alternative effective and efficient tool for the complex optimization of multiple hydropower reservoirs. The water resources in the river basin can be further utilized by the proposed method to cope with the increasingly serious climate change.

Geomechanical Modeling and Equivalent Circulating Density (ECD) Management- An Integrated Approach for Successfully Drilling and Managing Losses in Highly Depleted Sands

A mature field in offshore Sarawak, Malaysia, contains multiple reservoir cycles interbedded with weak shale and coals. Production from these reservoirs caused significant pressure depletion, as well as reduced fracture gradient and a narrower drilling mud weight window. An integrated approach among the multi-disciplinary team was required in the well planning process to maintain the planned drilling and completion costs. An improperly weighted mud may induce wellbore instability in weaker, but normally pressured, formations or mud losses in the heavily depleted reservoirs. Globally, mud losses are considered the most expensive well control operation. Hence, successful drilling and managing losses through depleted sands requires a comprehensive geomechanical modeling and wellbore stability analysis. A field scale geomechanical model was developed and validated using data from exploration and development wells from different phases of drilling in the study area. The stress path factor (SPF), which determines the reduction in fracture gradient with pore pressure depletion is crucial for defining drilling mud windows, is difficult to constrain in the absence of measured formation fracturing data in virgin and depleted reservoirs. A mud loss event in the depleted zone from a recent drilled well and regional information were used to estimate the range of SPF in the study area. Recorded bottom hole pressures from pressure while drilling (PWD) data suggested that the maximum equivalent circulating density (ECD) recorded was close or within the depleted section. The loss event was associated with reduced fracture gradient due to depletion from its pre-depleted range. This paper describes how geomechanical evaluation with effective well drilling practices and fit for purpose-drilling fluids have helped drilling through depleted reservoirs with ECD management. At the end, it shows a comparison of the predrill wellbore stability mud weight estimates with the actual mud weights used to successfully drill and complete the planned wells.

The Significant Impact of Intraformational Seal to Hydrocarbon Accumulation of Mixed Carbonate - Siliciclastic Sequences In Oligo-Miocene Interval, North Madura Platform, East Java Basin

The major reservoir within the North Madura Platform is the Oligo-Miocene Interval, which consists of oil and gas-bearing reservoirs, with multiple reservoir layers and multiple hydrocarbon contacts. The interval comprises of a stacked high frequency cycles of mixed carbonate-siliciclastic lithology component sitting in the paleo-high. It has become very important in the context of hydrocarbon accumulation since the components play very dissimilar roles and become reservoir-seal pairs, which resulted in the existence of intraformational seal. Based on the carbonate to siliciclastic ratio, from deeper to shallower interval, it can be divided into three cycles, namely first cycle with carbonate-dominated interval, second cycle with mixed carbonate-shale interval, and third cycle consists of massive carbonate sequences. The vertical hydrocarbon migration, both oil and gas, occurred within the known trap in the study area, filled the reservoirs from deeper to shallower interval with subject to seal capacity of each intraformational seal and leak points in the trap. The first cycle consisted of oil indicated that the seal breached as reservoir become fully saturated and some of oil and most of the gas leak. The second cycle, which consisted of multiple reservoir-seal pairs with oil and gas being accumulated depending on the seal strength. The third cycle, which is massive carbonate reservoir, is capped by thick marine shale as a roof seal that has been proven for gas being trapped. Better understanding on intrafomational seal, both micro and macro characteristics, can be highly beneficial to identify potential overlooked zone as well as contributing to the proper judgment on the likelihood of hydrocarbon accumulation.

Pressure Transient Analysis for a Finite-Conductivity Fractured Vertical Well Near a Leaky Fault in Anisotropic Linear Composite Reservoirs

Geologic discontinuities usually exist in subsurface permeable formations, where multiple reservoir regions with distinct properties are separated by linear leaky faults. This kind of heterogeneous reservoir is usually called a linear composite reservoir. Although many analytical/semi-analytical linear composite models have been established to investigate the pressure behavior for linear composite reservoirs, almost all of these models were aimed at vertical wells without hydraulic fracturing and there are few analytical/semi-analytical models of fractured vertical wells in linear composite reservoirs. This paper first derives the Laplace-space point source solution for anisotropic linear composite systems separated by a partially communicating fault. Then, superposition principle and fracture discrete scheme are employed to acquire the semi-analytical solution for finite-conductivity fractured vertical (FCFV) wells in anisotropic linear composite reservoirs with a fault. The proposed solution is validated against numerical solutions under different reservoir scenarios. The characteristic of the pressure behavior for an FCFV well in anisotropic linear composite reservoirs with a fault is discussed in detail. The proposed model can be employed to obtain accurate pressure response with high computational efficiency. It is a good start to further develop analytical/semi-analytical models for other complex well types in an anisotropic linear composite reservoir with a fault.

Influence of well management in the development of multiple reservoir sharing production facilities

Well prioritization rules on integrated production models are required for the interaction between reservoirs and restricted production systems, thus predicting the behavior of multiple reservoir sharing facilities. This study verified the impact of well management with an economic evaluation based on the distinct prioritizations by reservoir with different fluids. We described the impact of the well management method in a field development project using a consolidated methodology for production strategy optimization. We used a benchmark case based on two offshore fields, a light oil carbonate and a black-oil sandstone, with gas production constraint in the platform. The independent reservoir models were tested on three different approaches for platform production sharing: (Approach 1) fixed apportionment of platform production and injection, (Approach 2) dynamic flow-based apportionment, and (Approach 3) dynamic flow-based apportionment, including economic differences using weights for each reservoir. Approach 1 provided the intermediate NPV compared with the other approaches. On the other hand, it provided the lowest oil recovery. We observed that the exclusion of several wells in the light oil field led to a good valuation of the project, despite these wells producing a fluid with higher value. Approach 2 provided the lower NPV performance and intermediate oil recovery. We found that the well prioritization based on flow failed to capture the effects related to the different valuation of the fluids produced by the two reservoirs. Approach 3, which handled the type of fluids similarly to Approach 1, provided a greater NPV and oil recovery than the other approaches. The weight for each reservoir applied to well prioritization better captured the gains related to different valuation of the fluids produced by the two reservoirs. Dynamic prioritization with weights performed better results than fixed apportionment to shared platform capacities. We obtained different improvements in the project development optimization due to the anticipation of financial returns and CAPEX changes, due mainly from adequate well apportionment by different management algorithm. Well management algorithms implemented in traditional simulators are not developed to prioritize different reservoir wells separately, especially if there are different economic conditions exemplified here by a different valuation of produced fluids. This valuation should be taken into account in the short term optimization for wells.