How Can Sand Production Yield a Several-Fold Increase in Productivity: Experimental and Field Data
- H.H. Vaziri (Geomatrix Consultants) | E. Lemoine (Geomatrix Consultants) | I.D. Palmer (BP-Amoco) | J. McLennan (TerraTek) | R. Islam (Dalhousie University)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 1-4 October, Dallas, Texas
- Publication Date
- Document Type
- Conference Paper
- 2000. Society of Petroleum Engineers
- 5.8.5 Oil Sand, Oil Shale, Bitumen, 2.4.5 Gravel pack design & evaluation, 1.2.2 Geomechanics, 2.2.2 Perforating, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 1.10 Drilling Equipment, 1.8 Formation Damage, 2.4.3 Sand/Solids Control, 5.1.1 Exploration, Development, Structural Geology, 5.6.5 Tracers, 4.1.5 Processing Equipment, 5.8.3 Coal Seam Gas, 3.2.5 Produced Sand / Solids Management and Control, 2 Well Completion, 4.6 Natural Gas, 4.3.4 Scale
- 1 in the last 30 days
- 338 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 8.50|
|SPE Non-Member Price:||USD 25.00|
Centrifuge physical model tests were performed to study the mode of failure during sand production and its concomitant impact on the productivity index. The tests simulated seepage-induced failure around a vertical well. Results indicate that in the presence of a competent cap rock (1) sand production results in the formation of a cone-shaped enlarged cavity; (2) surface subsidence of the reservoir due to loss of sand mass which may result in opening of flow channels under the cap rock; (3) for a given wellbore pressure, sand production ceases once the enlarged cavity lowers the flowrate to sub-critical level; (4) flow becomes diverted towards the upper perfs where the cavity radius is largest; (5) flow rate increase varies between 5 to 50 times depending on whether the mode and volume of sanding is sufficient to result in the formation of flow channels. The study performed shows that (1) the location of perfs affects the mode and magnitude of sand production and the concomitant productivity, and (2) long-term productivity can be improved through managed sand production. Presence of a competent cap rock is the key for maximizing the productivity via sanding. These findings are consistent with some field cases where extraordinary increases in production were noted as a result of sanding. Sand production, if properly managed, can reduce the completion costs (e.g., by omitting or delaying installation of sand exclusion measures) and improve the long term productivity by removing the skin damage and also through creating voids and zones of higher porosity around the well and under the caprock.
The conventional practice in oil and gas recovery projects is to minimize sand production by installing sand exclusion measures such as liners and gravel packs. While in a number of field cases this is justified, often times such measures are employed prematurely resulting in not only redundant expenditure but also in diminishing well's productivity due to inevitable plugging of filters whose function is to stop the migration of the fines. There are many field cases that show seepage or drawdown induced sand production can be mitigated by a careful control of the flow rate which means that in the early stages of a well's life there is no need to use sand exclusion measures. Such measures, however, must be considered in mature reservoirs where a significant decline in the reservoir pressure can trigger sanding as the strains increase; this mode of sanding is generally referred to as depletion-induced sanding.
Over the past decade or so, an increasing number of studies (field, lab and numerical) have been performed that point to significant advantages of promoting sand production, as summarized in Palmer et al1. For instance, it is reasonable to suggest that creating mini sand bursts can remove or clean the near wellbore skin damage which may increase productivity by as much as 30%. By using well-established geomechanical concepts such events can be controlled quite reliably thus minimizing the risk of triggering large or on going sanding. A far more effective way of boosting production though is to create massive sand production. By massive, we imply sufficient loss of sand mass to render cavities and enhanced porosity regions (arising from loss of fines and shear induced dilation). Massive sand production can be applied to both new wells and existing wells although the former provides the most economical sense as it obviates the need for installing sand prevention measures. It must be noted that massive sand production is viable in reservoirs that have favourable geological properties and characteristics. Specifically, the reservoir must have either adequate cohesion or be capped by a competent rock layer such that a stable sand free condition can be achieved.
|File Size||630 KB||Number of Pages||12|