Devshali, Sagun (Oil and Natural Gas Corporation Ltd.) | Manchalwar, Vinod (Oil and Natural Gas Corporation Ltd.) | Deuri, Budhin (Oil and Natural Gas Corporation Ltd.) | Malhotra, Sanjay Kumar (Oil and Natural Gas Corporation Ltd.) | Prasad, Bulusu V.R.V. (Oil and Natural Gas Corporation Ltd.) | Yadav, Mahendra (Oil and Natural Gas Corporation Ltd.) | Kumar, Avinav (Oil and Natural Gas Corporation Ltd.) | Uniyal, Rishabh (Oil and Natural Gas Corporation Ltd.)
The paper describes the feasibility of revisiting old sands, for improving the recovery factors and enhancing production, which otherwise were already abandoned. The paper also outlines the systematic methods for predicting the onset of liquid loading in gas wells, evaluation of completions for optimization and comparison of various deliquification techniques. ONGC is operating in two gas fields in eastern and western regions in India. Earlier in both the fields, many sands had to be closed/isolated after the wells ceased to flow due to liquid loading in the absence of continuous deliquification. In order to predict liquid loading tendencies and identify opportunities for production enhancement, performance of 150 gas wells has been analyzed. To select most suitable deliquification technique for the present condition, all technically feasible methods have been evaluated and compared in order to get the maximum ultimate gas recovery possible.
After an extensive study, 3 wells were identified in the preliminary stage and SRP was selected as the most suitable Deliquification technique. Initially, two non-flowing wells, which had ceased due to liquid loading and were about to be abandoned, were selected. After SRP installation and sustained unloading of water for about 30 days, these wells started producing 12000 SCMD gas. In the third well, one of the top sands had earlier been isolated due to liquid loading and production history indicated that the isolated sand had a very good potential. Also, production from the well was declining in the current bottom operating sand as well due to liquid loading. Encouraged by the results that deliquification had yielded in the initial two gas wells, the isolated sand interval in the third well was opened again with the aim to revive production. The well was re-completed with SRP with both the reservoirs open. Before deliquification, the well was producing about 15000 SCMD gas from the bottom sand. After SRP installation and continuous deliquification, the well started producing gas at a stabilized rate of 45000 SCMD, thereby resulting in an additional gas recovery of 30000 SCMD for nearly one year as on date. The approach of putting in place continuous deliquification techniques has not only helped in enhancing production from the existing reservoirs, but has also opened up new avenues to revisit the earlier isolated / abandoned reservoirs for possible enhanced recoveries.
Majority of the Indian Oil Fields have gone well past the age of self-flow, with only a very few select wells currently producing crude utilizing the natural reservoir energy. It is a well-documented fact that the age of easy, light oil has passed and that, most of the new discoveries being made are those of either heavy or ultra-heavy crude oil types.
SRPs, ESPs, Jet pumps, Gas lift are the various modes of artificial lift currently under employment. However, all these methods fail when heavy oils are encountered. In such cases, these methods of artificial lift fail to provide the requisite lift for the crude to reach the surface. However, the Progressive Cavity Pumps (PCPs) have found great utility under conditions of heavy crude production. The spiral motion of the Pump cavity from suction to discharge causes jerk-free motion of the crude.
PC Pumps have distinctive advantage over the other methods, when heavy crudes along with significant sand cuts are to be produced. PC Pumps are also used on a large scale for de-watering of CBM wells.
In this paper, an extensive review of the available literature was done to study PC Pumps and the various advancements achieved through the years. Artificial lift selection methods were investigated and a comprehensive procedure enlisted to select the right type of lift which best suits the field/well.
An efficient and cost-effective completion is very critical in the mature brownfield of Mumbai High. Horizontal and multilateral wells are strategic completions in this oil reservoir because of their high productivity and larger drainage area. This paper deals with design optimization of slotted liner for horizontal wells in Mumbai High field of India.
A good horizontal completion must maintain the mechanical integrity of the wellbore without posing a significant flow restriction. In this respect, slotted and perforated liners are cost effective solutions in horizontal wells because they provide uniform reservoir drainage, wellbore stability and control of solid production. A slotted liner completion is preferred, because it results in better solid control and lesser flow convergence. However, the compounded effect of formation heterogeneity and formation damage on pressure loss is severe in these completions. A good design is essential to minimize pressure loss due to flow restrictions and to maintain the long term productivity of well.
The major challenge is to have an optimum slot size and geometry that minimizes slot plugging and near wellbore flow convergence losses. A keystone slot design with consideration for convergence loss is arrived to address this problem. The effect of parameters such as slot size and slot density on flow convergence pressure loss was taken into account for design optimization.
This paper covers the design, optimization and application of slotted liner completions with an objective to address solid control, completion economics, well productivity and long term well performance.